s  = "-------=>------------=>-------"
 while true do
   s.gsub!(/=>\-/,'-=>')
   s.gsub!(/=>$/,'<=')
 　s.gsub!(/\-<=/,'<=-')
 　s.gsub!(/^<=/,'=>')
 　s.gsub!(/=><=/,'<==>')
 　puts s
 end