void setup() {
  Serial.begin(9600); //Start serial communjcation at 9600 baud
  Serial.println("input number: ");
}

void loop() {
  //Check if  data is available in the Serial Monitor
  if (Serial.available() > 0) {
    //read the input from the serial monitor and convert it to an integer
  int angka = Serial.parseInt();
  Serial.read(); //Read and discard the newline character 
  Serial.println(angka); //Display the entered number
  }
}