const int greenLight1 = 2; // assign pin 2 to green light of traffic light 1
const int yellowLight1 = 3; // assign pin 3 to yellow light of traffic light 1
const int redLight1 = 4; // assign pin 4 to red light of traffic light 1

const int greenLight2 = 5; // assign pin 5 to green light of traffic light 2
const int yellowLight2 = 6; // assign pin 6 to yellow light of traffic light 2
const int redLight2 = 7; // assign pin 7 to red light of traffic light 2

void setup() {
  pinMode(greenLight1, OUTPUT); // set the pins as output
  pinMode(yellowLight1, OUTPUT);
  pinMode(redLight1, OUTPUT);
  pinMode(greenLight2, OUTPUT);
  pinMode(yellowLight2, OUTPUT);
  pinMode(redLight2, OUTPUT);
}

void loop() {
  digitalWrite(greenLight1, HIGH); // turn green light of traffic light 1 on
  digitalWrite(redLight2, HIGH); // turn red light of traffic light 2 on
  delay(5000); // wait for 5 seconds
  
  digitalWrite(greenLight1, LOW); // turn green light of traffic light 1 off
  digitalWrite(yellowLight1, HIGH); // turn yellow light of traffic light 1 on
  delay(2000); // wait for 2 seconds
  
  digitalWrite(yellowLight1, LOW); // turn yellow light of traffic light 1 off
  digitalWrite(redLight1, HIGH); // turn red light of traffic light 1 on
  
  digitalWrite(redLight2, LOW); // turn red light of traffic light 2 off
  digitalWrite(greenLight2, HIGH); // turn green light of traffic light 2 on
  delay(5000); // wait for 5 seconds
  
  digitalWrite(greenLight2, LOW); // turn green light of traffic light 2 off
  digitalWrite(yellowLight2, HIGH); // turn yellow light of traffic light 2 on
  delay(2000); // wait for 2 seconds
  
  digitalWrite(yellowLight2, LOW); // turn yellow light of traffic light 2 off
  digitalWrite(redLight2, HIGH); // turn red light of traffic light 2 on
}