startup

rednet.open("back")
while true dofile(
  local right = rs.getInput("right")
  local left = rs.getInput("left")
  if right then
    print("Train coming from right")
    rednet.send(
  elseif left then
    print("Train coming from left")
    rs.setOutput("front",true)
  end
os.pullEvent("redstone")
end