#define LED_RED 2
#define LED_YELLOW 4
#define LED_GREEN 3

void setup() {
pinMode(LED_RED, OUTPUT);
pinMode(LED_YELLOW, OUTPUT);
pinMode(LED_GREEN, OUTPUT);
// put your setup code here, to run once:
}

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

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

 digitalWrite(LED_GREEN,HIGH);
 delay(1000);
 digitalWrite(LED_GREEN,LOW);
}