#define LED_RED 13
#define LED_YELLOW 8
#define LED_GREEN 2

void setup(){
  pinMode(LED_RED, OUTPUT);
  pinMode(LED_YELLOW, OUTPUT);
  pinMode(LED_GREEN, OUTPUT);
}

void loop(){
    digitalWrite(LED_RED, HIGH);
    digitalWrite(LED_YELLOW, LOW);
    digitalWrite(LED_GREEN, LOW);
    delay(1000);
    
    digitalWrite(LED_RED, LOW);
    digitalWrite(LED_YELLOW, HIGH);
    digitalWrite(LED_GREEN, LOW);
    delay(1000);

    digitalWrite(LED_RED, LOW);
    digitalWrite(LED_YELLOW, LOW);
    digitalWrite(LED_GREEN, HIGH);
    delay(1000);

    digitalWrite(LED_RED, LOW);
    digitalWrite(LED_YELLOW, LOW);
    digitalWrite(LED_GREEN, LOW);
    delay(1000);
}