¿How to know the number of selected elements?

Rails
1

Hello everybody,

i’m working with the next code:

<%= I18n.t("tog_mail.plugin_name") %>

<% for folder in @folder.siblings %> <%= link_to folder.name, {:controller=>"messages",:action=>"index",:id=>folder.id} -%> (<%= folder.messages.unread.count%>) | <% end %> <%= link_to I18n.t("tog_mail.member.create_new_message"), new_member_message_url, {:class => "button mainaction add", :title => I18n.t("tog_mail.member.compose_new_message")} %>

<% form_tag member_remove_messages_path(@messages), :method => :delete
do -%>

<% for msg in @messages %> > <% cont = link_to msg.subject, member_message_path(:id => msg) %> <%end%> <% if @messages.blank? %> <% end %>
<%= I18n.t("tog_mail.model.subject") %> <%= I18n.t("tog_mail.model.from") %> <%= I18n.t("tog_mail.model.to") %> <%= I18n.t("tog_mail.model.when") %> Eliminar
<%= page_entries_info @messages, :entry_name => I18n.t('tog_mail.member.messages') %> <%= will_paginate @messages, :container => false %>
<%= msg.unread? ? content_tag(:strong, cont) : cont %> <%= (msg.from != current_user ) ? msg.from.login : I18n.t("tog_mail.member.you") %> <%= (msg.to != current_user ) ? msg.to.login : I18n.t("tog_mail.member.you") %> <%= msg.date %> <% form_for :message, :url => member_remove_message_path(msg), :method => :delete do -%> <%= submit_tag I18n.t("tog_mail.member.delete"), :type => "image", :src =>"/tog_core/images/ico/delete.gif" %> <% end -%>
<%= I18n.t("tog_mail.member.no_messages") %>

<%= link_to I18n.t("tog_mail.member.remove_all_selected_messages"), member_remove_messages_path(msg), :confirm => I18n.t("tog_mail.member.delete_confirmation"), :method => :delete, :class => "button delete" %>
<% end -%>

And i want to know the number of selected messages, and then i want to
remove this messages.

Thanks for your help.