Cab

local MODEM_SIDE = "bottom"
local SERVER_ID = 1;

local MAXIMUM_LEVEL = 2

rednet.open(MODEM_SIDE);

rednet.broadcast("stop");

function receiveInput()
    print("Enter Floor Number: ")
    local input = tonumber(read())

    if type(input) == "number" then
        if input > MAXIMUM_LEVEL or input <= 0  then
            print("Level not in bounds.")
            receiveInput()
            return
        end

        rednet.broadcast({input})

        receiveInput()
        return
    else
        print("You're bad. Use an actual number.")
        receiveInput()
        return
    end

end

receiveInput();