int DELAY_TIME = 3000;

void setup() {
  // put your setup code here, to run once:
  pinMode(A5,OUTPUT);
  pinMode(A4,OUTPUT);
  pinMode(A3,OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:

  // Green
  digitalWrite(A5, HIGH);
  delay(DELAY_TIME);

  // Yellow
  digitalWrite(A5, LOW);
  digitalWrite(A4, HIGH);
  delay(1000);

  // Red  
  digitalWrite(A4, LOW);
  digitalWrite(A3, HIGH);
  delay(DELAY_TIME);
  digitalWrite(A3, LOW);
}