Potater

Users= {}
function isUser(User)
   for i=1,#Users do
      if (Users[i] == User) then
         return true
      end
   end
   return false
end

function loadUser()
   Users= {}
   path= fs.open('Users','r')
   while true do
      temp= path.readLine()
      if (temp == nil) then break end
      Users[#Users+1]= temp
   end
end

while true do
   loadUser()
   event,a,b= os.pullEvent()
   if (event == 'player') then
      term.clear()
      term.setCursorPos(1,1)
      if (not isUser(b)) then
         print('Start')
         time= 0
         rs.setOutput('left',true)
         while true do
            time= time+1
            print(time,'/3')
            if (time >=3) then
               rs.setOutput('left',false)
               break
            end
            sleep(1)
         end
         Users[#Users+1]= b
         path= fs.open('Users','w')
         for i=1,#Users do
            path.writeLine(Users[i])
         end
         path.close()
         print('Finish')
      else
         print('Error')
      end
   end
end