void setup() {
  // put your setup code here, to run once:
#define LED1_PIN 12
#define LED_2 11
#define LED_3 10
#define LED_4 9
pinMode(LED1_PIN, OUTPUT);
pinMode(LED_2, OUTPUT);
pinMode(LED_3, OUTPUT);
pinMode(LED_4, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(LED1_PIN, HIGH);
digitalWrite(LED_2, LOW);
digitalWrite(LED_3, HIGH);
digitalWrite(LED_4, LOW);
delay(500);

digitalWrite(LED1_PIN, LOW);
digitalWrite(LED_2, HIGH);
digitalWrite(LED_3, LOW);
digitalWrite(LED_4, HIGH);
delay(500);

}