startup

rs.setOutput("top", true)
local exitTime = 10 -- change to whatever you want
while true do
  if rs.getAnalogInput("front")<15 then
print (rs.getAnalogInput("front"))
        local timer = os.startTimer(exitTime) -- starts the timer
       while true do
        local evt, arg = os.pullEvent() -- wait for an event
         if evt == "timer" then
           if arg == timer then -- check if it's the correct timer
         --   print ("timer stoped")
             break -- break the loop
           end
         elseif (evt == "redstone" and rs.getInput("left")) then
     --  print ("timer restart")
           timer = os.startTimer(exitTime) -- restarts the timer
        end
      end
      rs.setOutput("top", false)
      sleep(0.2)
      rs.setOutput("top", true)

     end

sleep(0.5)
end