int ledMerah = 13;
int ledHijau = 12;
int ledBiru = 11;

void setup() {
  pinMode(ledMerah, OUTPUT);
  pinMode(ledHijau, OUTPUT);
  pinMode(ledBiru, OUTPUT);
}

void loop() {
  digitalWrite(ledMerah, HIGH);
  digitalWrite(ledHijau, LOW);
  digitalWrite(ledBiru, LOW);
  delay(1000);

  digitalWrite(ledMerah, LOW);
  digitalWrite(ledHijau, HIGH);
  digitalWrite(ledBiru, LOW);
  delay(1000);

  digitalWrite(ledMerah, LOW);
  digitalWrite(ledHijau, LOW);
  digitalWrite(ledBiru, HIGH);
  delay(1000);

  digitalWrite(ledMerah, LOW);
  digitalWrite(ledHijau, HIGH);
  digitalWrite(ledBiru, LOW);
  delay(1000);
}