#define RED_LED    13
#define YELLOW_LED 12
#define GREEN_LED  14

void setup() {
  pinMode(RED_LED, OUTPUT);
  pinMode(YELLOW_LED, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);
}

void loop() {
  // Red
  digitalWrite(RED_LED, HIGH);
  delay(2000);  // Red stays ON for 5 seconds

  // Red and Yellow together
  digitalWrite(YELLOW_LED, HIGH);
  delay(2000);  // Red and Yellow together for 2 seconds

  // Green
  digitalWrite(RED_LED, LOW);
  digitalWrite(YELLOW_LED, LOW);
  digitalWrite(GREEN_LED, HIGH);
  delay(2000);  // Green stays ON for 5 seconds

  // Yellow
  digitalWrite(GREEN_LED, LOW);
  digitalWrite(YELLOW_LED, HIGH);
  delay(2000);  // Yellow stays ON for 2 seconds before switching to Red again

  digitalWrite(YELLOW_LED, LOW);
}