diff --git a/Gemfile.lock b/Gemfile.lock
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -194,6 +194,8 @@
       net-protocol
       timeout
     nio4r (2.5.8)
+    nokogiri (1.13.8-x86_64-darwin)
+      racc (~> 1.4)
     nokogiri (1.13.8-x86_64-linux)
       racc (~> 1.4)
     popper_js (2.11.6)
@@ -267,6 +269,7 @@
       actionpack (>= 5.2)
       activesupport (>= 5.2)
       sprockets (>= 3.0.0)
+    sqlite3 (1.5.0-x86_64-darwin)
     sqlite3 (1.5.0-x86_64-linux)
     strscan (3.0.4)
     temple (0.8.2)
@@ -293,6 +296,7 @@
     zeitwerk (2.6.0)
 
 PLATFORMS
+  x86_64-darwin-20
   x86_64-linux
 
 DEPENDENCIES
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -15,9 +15,8 @@
   WHITELIST_IP_CONF_KEY = 'right.whitelist_ip'
 
   #report and redirect for unauthorized activities
-  def unauthorized_redirect(notice = 'You are not authorized to view the page you requested')
-    flash[:notice] = notice
-    redirect_to login_main_path
+  def unauthorized_redirect(msg = 'You are not authorized to view the page you requested')
+    redirect_to login_main_path, alert: msg
   end
 
   # Returns the current logged-in user (if any).
@@ -46,30 +45,18 @@
     return true
   end
 
-  #admin always count as every roles
-  def role_authorization(roles)
+  def authorization_by_roles(allowed_roles)
     return false unless check_valid_login
-    user = User.find(session[:user_id])
-    return true if user.admin?
+    return true if @current_user.admin?
     roles.each do |r|
-      return true if user.has_role?(r)
+      return true if @current_user.has_role?(r)
     end
     unauthorized_redirect
   end
 
-  def authorization_by_roles(allowed_roles)
-    return false unless check_valid_login
-    unless @current_user.roles.detect { |role| allowed_roles.member?(role.name) }
-      unauthorized_redirect
-      return false
-    end
-  end
-
   def testcase_authorization
     #admin always has privileged
-    if @current_user.admin?
-      return true
-    end
+    return true if @current_user.admin?
 
     unauthorized_redirect unless GraderConfiguration["right.view_testcase"]
   end
diff --git a/app/controllers/login_controller.rb b/app/controllers/login_controller.rb
--- a/app/controllers/login_controller.rb
+++ b/app/controllers/login_controller.rb
@@ -1,7 +1,7 @@
 class LoginController < ApplicationController
 
   @@authenticators = []
-  
+
   def index
     # show login screen
     reset_session
@@ -11,14 +11,12 @@
   def login
     user = get_authenticated_user(params[:login], params[:password])
     unless user
-      flash[:notice] = 'Wrong password'
-      redirect_to :controller => 'main', :action => 'login'
+      redirect_to login_main_path, alert: 'Wrong password'
       return
     end
 
     if (!GraderConfiguration['right.bypass_agreement']) and (!params[:accept_agree]) and !user.admin?
-      flash[:notice] = 'You must accept the agreement before logging in'
-      redirect_to :controller => 'main', :action => 'login'
+      redirect_to login_main_path, alert: 'You must accept the agreement before logging in'
       return
     end
 
@@ -60,14 +58,14 @@
       site = nil
     end
     if site==nil
-      flash[:notice] = 'Wrong site'
+      flash[:alert] = 'Wrong site'
       redirect_to :controller => 'main', :action => 'login'  and return
     end
     if (site.password) and (site.password == params[:login][:password])
       session[:site_id] = site.id
       redirect_to :controller => 'site', :action => 'index'
     else
-      flash[:notice] = 'Wrong site password'
+      flash[:alert] = 'Wrong site password'
       redirect_to :controller => 'site', :action => 'login'
     end
   end
diff --git a/app/controllers/main_controller.rb b/app/controllers/main_controller.rb
--- a/app/controllers/main_controller.rb
+++ b/app/controllers/main_controller.rb
@@ -18,9 +18,8 @@
   #reset login, clear session
   #front page
   def login
-    saved_notice = flash[:notice]
-    reset_session
-    flash.now[:notice] = saved_notice
+    #saved_notice = flash[:notice]
+    #flash[:notice] = saved_notice
     @remote_ip = request.remote_ip
 
     # EXPERIMENT:
diff --git a/app/controllers/submissions_controller.rb b/app/controllers/submissions_controller.rb
--- a/app/controllers/submissions_controller.rb
+++ b/app/controllers/submissions_controller.rb
@@ -2,7 +2,7 @@
   before_action :set_submission, only: [:show,:download,:compiler_msg,:rejudge,:set_tag, :edit]
   before_action :check_valid_login
   before_action :submission_authorization, only: [:show, :download, :edit]
-  before_action only: [:rejudge, :set_tag] do role_authorization([:ta]) end
+  before_action only: [:rejudge, :set_tag] do authorization_by_roles([:ta]) end
 
   # GET /submissions
   # GET /submissions.json
diff --git a/app/controllers/tags_controller.rb b/app/controllers/tags_controller.rb
--- a/app/controllers/tags_controller.rb
+++ b/app/controllers/tags_controller.rb
@@ -25,7 +25,7 @@
     @tag = Tag.new(tag_params)
 
     if @tag.save
-      redirect_to @tag, notice: 'Tag was successfully created.'
+      redirect_to tags_path, notice: 'Tag was successfully created.'
     else
       render :new
     end
diff --git a/app/views/groups/index.html.haml b/app/views/groups/index.html.haml
--- a/app/views/groups/index.html.haml
+++ b/app/views/groups/index.html.haml
@@ -16,7 +16,7 @@
         %td= group.description
         %td= toggle_button(group.enabled?, toggle_group_path(group), "group-enabled-#{group.id}", block: ' ')
         %td
-          = link_to 'Edit members and problems', group, class: 'btn btn-secondary btn-sm'
+          = link_to 'Edit members and problems', group, class: 'btn btn-info btn-sm'
           = link_to 'Destroy', group, :method => :delete, :data => { :confirm => 'Are you sure?' }, class: 'btn btn-danger btn-sm'
 
 %br
diff --git a/app/views/layouts/_header.html.haml b/app/views/layouts/_header.html.haml
--- a/app/views/layouts/_header.html.haml
+++ b/app/views/layouts/_header.html.haml
@@ -82,7 +82,7 @@
             %a.nav-link{href: profile_users_path}
               %span.mi.mi-bs.md-18 settings
         %li.nav-item
-          %a.nav-link{href: login_main_path}
+          %a.nav-link{href: logout_main_path}
             %span.mi.mi-bs.md-18 exit_to_app
             = @current_user.full_name
 :javascript
diff --git a/app/views/main/_login_box.html.haml b/app/views/main/_login_box.html.haml
--- a/app/views/main/_login_box.html.haml
+++ b/app/views/main/_login_box.html.haml
@@ -7,9 +7,8 @@
       .card-subtitle=t 'login.message'
 
       - if flash[:notice]
-        %hr/
-        %b= flash[:notice]
-        %hr/
+        .alert.alert-danger
+          = flash[:notice]
 
       .card
         .card-body{ style: "background: #eeeeff;"}
diff --git a/app/views/tags/_form.html.haml b/app/views/tags/_form.html.haml
--- a/app/views/tags/_form.html.haml
+++ b/app/views/tags/_form.html.haml
@@ -1,22 +1,7 @@
-= form_for @tag do |f|
-  - if @tag.errors.any?
-    #error_explanation
-      %h2= "#{pluralize(@tag.errors.count, "error")} prohibited this tag from being saved:"
-      %ul
-        - @tag.errors.full_messages.each do |msg|
-          %li= msg
-
+= simple_form_for @tag do |f|
   .row
     .col-md-6
-      .form-group.field
-        = f.label :name
-        = f.text_field :name, class: 'form-control'
-      .form-group.field
-        = f.label :description
-        = f.text_area :description, class: 'form-control'
-      .form-group.field
-        = f.label :public
-        = f.text_field :public, class: 'form-control'
-      .actions
-        = f.submit 'Save', class: 'btn btn-primary'
-    .col-md-6
+      = f.input :name
+      = f.input :description
+      = f.input :public
+      = f.submit 'Save', class: 'btn btn-primary'
diff --git a/app/views/tags/index.html.haml b/app/views/tags/index.html.haml
--- a/app/views/tags/index.html.haml
+++ b/app/views/tags/index.html.haml
@@ -18,9 +18,9 @@
         %td= tag.name
         %td= tag.description
         %td= tag.public
-        %td= link_to 'Show', tag
-        %td= link_to 'Edit', edit_tag_path(tag)
-        %td= link_to 'Destroy', tag, :method => :delete, :data => { :confirm => 'Are you sure?' }
+        %td= link_to 'Show', tag, class: 'btn btn-info'
+        %td= link_to 'Edit', edit_tag_path(tag), class: 'btn btn-info'
+        %td= button_to 'Destroy', tag, :method => :delete, :data => { :confirm => 'Are you sure?' }, class: 'btn btn-danger'
 
 %br
 
diff --git a/app/views/user_admin/index.html.haml b/app/views/user_admin/index.html.haml
--- a/app/views/user_admin/index.html.haml
+++ b/app/views/user_admin/index.html.haml
@@ -76,8 +76,8 @@
       %td= toggle_button(user.enabled?, toggle_enable_user_path(user),"toggle_enable_user_#{user.id}")
       %td= user.last_ip
       %td= link_to 'Clear IP', {:action => 'clear_last_ip', :id => user, :page=>params[:page]}, :confirm => 'This will reset last logging in ip of the user, are you sure?', class: 'btn btn-secondary btn-sm btn-block'
-      %td= link_to 'Show', {:action => 'show', :id => user}, class: 'btn btn-secondary btn-sm btn-block'
-      %td= link_to 'Edit', {:action => 'edit', :id => user}, class: 'btn btn-secondary btn-sm btn-block'
+      %td= link_to 'Show', {:action => 'show', :id => user}, class: 'btn btn-info btn-sm btn-block'
+      %td= link_to 'Edit', {:action => 'edit', :id => user}, class: 'btn btn-info btn-sm btn-block'
       %td= link_to 'Destroy', {action: :destroy, id: user}, data: {confirm: 'Are you sure?'}, method: :delete, class: 'btn btn-danger btn-sm btn-block'
 %br/
 = link_to '+ New user', { :action => 'new' }, { class: 'btn btn-success '}
diff --git a/db/schema.rb b/db/schema.rb
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -11,7 +11,7 @@
 # It's strongly recommended that you check this file into your version control system.
 
 ActiveRecord::Schema[7.0].define(version: 2022_09_27_074644) do
-  create_table "active_storage_attachments", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+  create_table "active_storage_attachments", charset: "latin1", force: :cascade do |t|
     t.string "name", null: false
     t.string "record_type", null: false
     t.bigint "record_id", null: false
@@ -21,7 +21,7 @@
     t.index ["record_type", "record_id", "name", "blob_id"], name: "index_active_storage_attachments_uniqueness", unique: true
   end
 
-  create_table "active_storage_blobs", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+  create_table "active_storage_blobs", charset: "latin1", force: :cascade do |t|
     t.string "key", null: false
     t.string "filename", null: false
     t.string "content_type"
@@ -33,15 +33,15 @@
     t.index ["key"], name: "index_active_storage_blobs_on_key", unique: true
   end
 
-  create_table "active_storage_variant_records", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+  create_table "active_storage_variant_records", charset: "latin1", force: :cascade do |t|
     t.bigint "blob_id", null: false
     t.string "variation_digest", null: false
     t.index ["blob_id", "variation_digest"], name: "index_active_storage_variant_records_uniqueness", unique: true
   end
 
-  create_table "announcements", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "announcements", id: :integer, charset: "utf8", force: :cascade do |t|
     t.string "author"
-    t.text "body"
+    t.text "body", size: :medium
     t.boolean "published"
     t.datetime "created_at", precision: nil, null: false
     t.datetime "updated_at", precision: nil, null: false
@@ -52,7 +52,7 @@
     t.boolean "on_nav_bar", default: false
   end
 
-  create_table "contests", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "contests", id: :integer, charset: "utf8", force: :cascade do |t|
     t.string "title"
     t.boolean "enabled"
     t.datetime "created_at", precision: nil, null: false
@@ -60,39 +60,39 @@
     t.string "name"
   end
 
-  create_table "contests_problems", id: false, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "contests_problems", id: false, charset: "utf8", force: :cascade do |t|
     t.integer "contest_id"
     t.integer "problem_id"
   end
 
-  create_table "contests_users", id: false, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "contests_users", id: false, charset: "utf8", force: :cascade do |t|
     t.integer "contest_id"
     t.integer "user_id"
   end
 
-  create_table "countries", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "countries", id: :integer, charset: "utf8", force: :cascade do |t|
     t.string "name"
     t.datetime "created_at", precision: nil, null: false
     t.datetime "updated_at", precision: nil, null: false
   end
 
-  create_table "descriptions", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
-    t.text "body"
+  create_table "descriptions", id: :integer, charset: "utf8", force: :cascade do |t|
+    t.text "body", size: :medium
     t.boolean "markdowned"
     t.datetime "created_at", precision: nil, null: false
     t.datetime "updated_at", precision: nil, null: false
   end
 
-  create_table "grader_configurations", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "grader_configurations", id: :integer, charset: "utf8", force: :cascade do |t|
     t.string "key"
     t.string "value_type"
     t.string "value"
     t.datetime "created_at", precision: nil, null: false
     t.datetime "updated_at", precision: nil, null: false
-    t.text "description"
+    t.text "description", size: :medium
   end
 
-  create_table "grader_processes", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "grader_processes", id: :integer, charset: "utf8", force: :cascade do |t|
     t.string "host"
     t.integer "pid"
     t.string "mode"
@@ -123,7 +123,7 @@
     t.index ["user_id", "group_id"], name: "index_groups_users_on_user_id_and_group_id"
   end
 
-  create_table "heart_beats", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "heart_beats", id: :integer, charset: "latin1", force: :cascade do |t|
     t.integer "user_id"
     t.string "ip_address"
     t.datetime "created_at", precision: nil, null: false
@@ -132,14 +132,14 @@
     t.index ["updated_at"], name: "index_heart_beats_on_updated_at"
   end
 
-  create_table "languages", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "languages", id: :integer, charset: "utf8", force: :cascade do |t|
     t.string "name", limit: 10
     t.string "pretty_name"
     t.string "ext", limit: 10
     t.string "common_ext"
   end
 
-  create_table "logins", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "logins", id: :integer, charset: "latin1", force: :cascade do |t|
     t.integer "user_id"
     t.string "ip_address"
     t.datetime "created_at", precision: nil, null: false
@@ -147,18 +147,18 @@
     t.index ["user_id"], name: "index_logins_on_user_id"
   end
 
-  create_table "messages", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "messages", id: :integer, charset: "utf8", force: :cascade do |t|
     t.integer "sender_id"
     t.integer "receiver_id"
     t.integer "replying_message_id"
-    t.text "body"
+    t.text "body", size: :medium
     t.boolean "replied"
     t.datetime "created_at", precision: nil, null: false
     t.datetime "updated_at", precision: nil, null: false
   end
 
-  create_table "problems", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
-    t.string "name", limit: 30
+  create_table "problems", id: :bigint, default: nil, charset: "utf8", force: :cascade do |t|
+    t.string "name", limit: 100
     t.string "full_name"
     t.integer "full_score"
     t.date "date_added"
@@ -174,45 +174,45 @@
     t.boolean "markdown"
   end
 
-  create_table "problems_tags", id: :integer, charset: "latin1", force: :cascade do |t|
-    t.integer "problem_id"
+  create_table "problems_tags", id: :bigint, default: nil, charset: "latin1", force: :cascade do |t|
+    t.bigint "problem_id"
     t.integer "tag_id"
     t.index ["problem_id", "tag_id"], name: "index_problems_tags_on_problem_id_and_tag_id", unique: true
     t.index ["problem_id"], name: "index_problems_tags_on_problem_id"
     t.index ["tag_id"], name: "index_problems_tags_on_tag_id"
   end
 
-  create_table "rights", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "rights", id: :integer, charset: "utf8", force: :cascade do |t|
     t.string "name"
     t.string "controller"
     t.string "action"
   end
 
-  create_table "rights_roles", id: false, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "rights_roles", id: false, charset: "utf8", force: :cascade do |t|
     t.integer "right_id"
     t.integer "role_id"
     t.index ["role_id"], name: "index_rights_roles_on_role_id"
   end
 
-  create_table "roles", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "roles", id: :integer, charset: "utf8", force: :cascade do |t|
     t.string "name"
   end
 
-  create_table "roles_users", id: false, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "roles_users", id: false, charset: "utf8", force: :cascade do |t|
     t.integer "role_id"
     t.integer "user_id"
     t.index ["user_id"], name: "index_roles_users_on_user_id"
   end
 
-  create_table "sessions", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "sessions", id: :integer, charset: "utf8", force: :cascade do |t|
     t.string "session_id"
-    t.text "data"
+    t.text "data", size: :medium
     t.datetime "updated_at", precision: nil
     t.index ["session_id"], name: "index_sessions_on_session_id"
     t.index ["updated_at"], name: "index_sessions_on_updated_at"
   end
 
-  create_table "sites", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "sites", id: :integer, charset: "utf8", force: :cascade do |t|
     t.string "name"
     t.boolean "started"
     t.datetime "start_time", precision: nil
@@ -222,14 +222,23 @@
     t.string "password"
   end
 
-  create_table "submission_view_logs", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "solutions", charset: "latin1", force: :cascade do |t|
+    t.string "solution"
+    t.bigint "problem_id"
+    t.bigint "submission_id"
+    t.integer "type"
+    t.index ["problem_id"], name: "index_solutions_on_problem_id"
+    t.index ["submission_id"], name: "index_solutions_on_submission_id"
+  end
+
+  create_table "submission_view_logs", id: :integer, charset: "latin1", force: :cascade do |t|
     t.integer "user_id"
     t.integer "submission_id"
     t.datetime "created_at", precision: nil, null: false
     t.datetime "updated_at", precision: nil, null: false
   end
 
-  create_table "submissions", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "submissions", id: :bigint, default: nil, charset: "utf8", force: :cascade do |t|
     t.integer "user_id"
     t.integer "problem_id"
     t.integer "language_id"
@@ -237,10 +246,10 @@
     t.binary "binary"
     t.datetime "submitted_at", precision: nil
     t.datetime "compiled_at", precision: nil
-    t.text "compiler_message"
+    t.text "compiler_message", size: :medium
     t.datetime "graded_at", precision: nil
     t.integer "points"
-    t.text "grader_comment"
+    t.text "grader_comment", size: :medium
     t.integer "number"
     t.string "source_filename"
     t.float "max_runtime"
@@ -261,7 +270,7 @@
     t.datetime "updated_at", precision: nil, null: false
   end
 
-  create_table "tasks", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "tasks", id: :integer, charset: "utf8", force: :cascade do |t|
     t.integer "submission_id"
     t.datetime "created_at", precision: nil
     t.integer "status"
@@ -270,15 +279,15 @@
     t.index ["submission_id"], name: "index_tasks_on_submission_id"
   end
 
-  create_table "test_pairs", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "test_pairs", id: :integer, charset: "utf8", force: :cascade do |t|
     t.integer "problem_id"
-    t.text "input", size: :medium
-    t.text "solution", size: :medium
+    t.text "input", size: :long
+    t.text "solution", size: :long
     t.datetime "created_at", precision: nil, null: false
     t.datetime "updated_at", precision: nil, null: false
   end
 
-  create_table "test_requests", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "test_requests", id: :integer, charset: "utf8", force: :cascade do |t|
     t.integer "user_id"
     t.integer "problem_id"
     t.integer "submission_id"
@@ -289,7 +298,7 @@
     t.datetime "updated_at", precision: nil, null: false
     t.datetime "submitted_at", precision: nil
     t.datetime "compiled_at", precision: nil
-    t.text "compiler_message"
+    t.text "compiler_message", size: :medium
     t.datetime "graded_at", precision: nil
     t.string "grader_comment"
     t.datetime "created_at", precision: nil, null: false
@@ -306,12 +315,12 @@
     t.integer "score"
     t.text "input", size: :long
     t.text "sol", size: :long
-    t.datetime "created_at", precision: nil
-    t.datetime "updated_at", precision: nil
+    t.datetime "created_at", precision: nil, null: false
+    t.datetime "updated_at", precision: nil, null: false
     t.index ["problem_id"], name: "index_testcases_on_problem_id"
   end
 
-  create_table "user_contest_stats", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "user_contest_stats", id: :integer, charset: "utf8", force: :cascade do |t|
     t.integer "user_id"
     t.datetime "started_at", precision: nil
     t.datetime "created_at", precision: nil, null: false
@@ -319,7 +328,7 @@
     t.boolean "forced_logout"
   end
 
-  create_table "users", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
+  create_table "users", id: :integer, charset: "utf8", force: :cascade do |t|
     t.string "login", limit: 50
     t.string "full_name"
     t.string "hashed_password"
@@ -331,10 +340,10 @@
     t.boolean "activated", default: false
     t.datetime "created_at", precision: nil
     t.datetime "updated_at", precision: nil
+    t.string "section"
     t.boolean "enabled", default: true
     t.string "remark"
     t.string "last_ip"
-    t.string "section"
     t.integer "default_language"
     t.index ["login"], name: "index_users_on_login", unique: true
   end
@@ -343,4 +352,6 @@
   add_foreign_key "active_storage_variant_records", "active_storage_blobs", column: "blob_id"
   add_foreign_key "problems_tags", "problems"
   add_foreign_key "problems_tags", "tags"
+  add_foreign_key "solutions", "problems"
+  add_foreign_key "solutions", "submissions"
 end