#define RED_LED 5
#define GREEN_LED 4
#define YELLOW_LED 2

void setup() {
  Serial.begin(115200);

  pinMode(RED_LED, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);
  pinMode(YELLOW_LED, OUTPUT);
}


void loop() {
  digitalWrite(RED_LED, HIGH);
  delay(500);
  digitalWrite(RED_LED, LOW);

  digitalWrite(GREEN_LED, HIGH);
  delay(500);
  digitalWrite(GREEN_LED, LOW);

  digitalWrite(YELLOW_LED, HIGH);
  delay(500);
  digitalWrite(YELLOW_LED, LOW);
}