Puzzle door

redstone.setOutput("back",false)
redstone.setOutput("front",false)

function open()
	if not redstone.getOutput("front") then
		for i=1,3 do
			redstone.setOutput("front",true)
			os.sleep(0.4)
			redstone.setOutput("front",false)
			os.sleep(0.4)
		end
	end
	redstone.setOutput("front",true)
end

while true do
	if redstone.getInput("back") then
		redstone.setOutput("back",true)
		open()
		os.sleep(1000)
	else
		os.sleep(0.1)
	end
end