// Pin assignments
const int redPin = 23;
const int yellowPin = 22;
const int greenPin = 21;

void setup() {
  // Set pin modes
  pinMode(redPin, OUTPUT);
  pinMode(yellowPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
}

void loop() {
  // Red light
  digitalWrite(redPin, HIGH);
  digitalWrite(yellowPin, LOW);
  digitalWrite(greenPin, LOW);
  delay(5000);  // Red light duration

  // Red and yellow lights (transition from red to green)
  digitalWrite(redPin, HIGH);
  digitalWrite(yellowPin, HIGH);
  digitalWrite(greenPin, LOW);
  delay(2000);  // Red and yellow light duration

  // Green light
  digitalWrite(redPin, LOW);
  digitalWrite(yellowPin, LOW);
  digitalWrite(greenPin, HIGH);
  delay(5000);  // Green light duration

  // Yellow light
  digitalWrite(redPin, LOW);
  digitalWrite(yellowPin, HIGH);
  digitalWrite(greenPin, LOW);
  delay(2000);  // Yellow light duration
}