const int greenLED = 2; 
const int yellowLED = 7; 
const int redLED = 11; 
void setup() {
  
  pinMode(greenLED, OUTPUT);
  pinMode(yellowLED, OUTPUT);
  pinMode(redLED, OUTPUT);
}

void loop() {
  
  digitalWrite(greenLED, HIGH);
  delay(5000);

  digitalWrite(greenLED, LOW);
  digitalWrite(yellowLED, HIGH);
  delay(2000);

  digitalWrite(yellowLED, LOW);
  digitalWrite(redLED, HIGH);
  delay(5000);

  digitalWrite(redLED, LOW);
}