#define RED 2
#define YELLOW 3
#define GREEN 4

void setup() {
  pinMode(RED, OUTPUT);
  pinMode(YELLOW, OUTPUT);
  pinMode(GREEN, OUTPUT);
}

void loop() {
    // start with red light for 5 seconds
    digitalWrite(RED, HIGH);
    digitalWrite(YELLOW, LOW);
    digitalWrite(GREEN, LOW);
    delay(5000);

    // Yellow light for 2 second
    digitalWrite(RED, LOW);
    digitalWrite(YELLOW, HIGH);
    delay(2000);

    // Green light for 5 seconds
    digitalWrite(YELLOW, LOW);
    digitalWrite(GREEN, HIGH);
    delay(5000);
}