void setup() {
  // put your setup code here, to run once:
  pinMode(11, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(13, OUTPUT);
  Serial.begin(9600);
}

void kelip_kuning() {
  for (int i=1; i<4; i++){
    digitalWrite(12, HIGH);
    delay(500);
    digitalWrite(12, LOW);
    delay(500);
  }
}

int tambah(int a, int b){
  int c;
  c=a+b;
  return c;
}

void loop() {
  // put your main code here, to run repeatedly:

  digitalWrite(11, HIGH);
  digitalWrite(12, LOW);
  digitalWrite(13, LOW);
  delay(2000);
  digitalWrite(11, LOW);
  Serial.println(tambah(1,3));
  kelip_kuning();
  digitalWrite(13, HIGH);
  delay(2000);
  digitalWrite(13, LOW);
  kelip_kuning();
}