const int ledRed1 = 2, ledYellow1 = 3, ledGreen1 = 4,
         ledRed2 = 5, ledYellow2 = 6, ledGreen2 = 7;

void setup() {
  pinMode(ledRed1, OUTPUT);
  pinMode(ledYellow1, OUTPUT);
  pinMode(ledGreen1, OUTPUT);
  pinMode(ledRed2, OUTPUT);
  pinMode(ledYellow2, OUTPUT);
  pinMode(ledGreen2, OUTPUT);
}

void loop() {
  for (int i = 0; i < 2; i++) {
    digitalWrite(ledRed1 + i * 3, HIGH);  // Nyalakan lampu merah atau hijau bergantian
    digitalWrite(ledGreen1 + (1 - i) * 3, HIGH);
    delay(5000);

    digitalWrite(ledRed1 + i * 3, LOW);
    digitalWrite(ledGreen1 + (1 - i) * 3, LOW);

    // Lampu kuning berkedip
    for (int j = 0; j < 3; j++) {
      digitalWrite(ledYellow1 + i * 3, HIGH);
      digitalWrite(ledYellow2 + i * 3, HIGH);
      delay(250);
      digitalWrite(ledYellow1 + i * 3, LOW);
      digitalWrite(ledYellow2 + i * 3, LOW);
      delay(250);
    }
  }
}