function clearScreen()
  term.clear()
  term.setCursorPos(1,1)
end

while true do
  clearScreen()
  print("Welcome to The Bank!")
  print("Press 1 for a new user")
  print("Press 2 for an existing user")

  local ect, key = os.pullEvent("key")
  local modem = peripheral.wrap("back")
  if key == 2 then
    --user wants to create a new account
    clearScreen()
    print("Register")
    write("Username: ")
    username = read()
    clearScreen()
    print("Register")
    write("Password: ")
    password = read("*")
    print("Waiting for server...")
    modem.transmit(1,1,"register`"..username.."`"..password)
    modem.open(1)
    local _, side, freq, rfreq, message = os.pullEvent("modem_message")
    if messsage == "409" then
      print("This user is already registered!")
    else
      print("User registered!")
    end
    os.sleep(1)
  else
    --user just wants to login
    clearScreen()
    print("Login")
    write("Username: ")
    username = read()
    clearScreen()
    print("Login")
    write("Password:")
    password = read("*")
    clearScreen()
    modem.transmit(1,1,"login`"..username.."`"..password)

    modem.open(1)
    local _, side, freq, rfreq, message = os.pullEvent("modem_message")
    if message == "403" then
      print("The user '"..username.."' is not a valid user!")
      else if message == "403" then
        print("There is no user called "..username.."!")
      else
        textutils.slowPrint("Your balance is "..message)
      end
    end
os.sleep(4)
  end
end