Lift control

CURRENT_FLOOR = 1
SECRET = 'first'

rednet.open('back')

while true do
    print('Which floor do you need?')
    write('Enter the number: ')
    floor = read()
    floor = tonumber(floor)

    if floor == CURRENT_FLOOR then
        print('You are already at this floor')
    elseif floor == nil or floor < 0 or floor > 3 then
        print('Wrong input, try again')
    else
        print('Activating teleporter...')
        rednet.broadcast(floor, SECRET)
    end
end