const int redLedPin = 21;     
const int yellowLedPin = 22;
const int greenLedPin = 23;
const int blueLedPin = 19; 
const int buttonPin = 18;  
volatile bool pedestrianPressed = false; 
void handleButtonPress() {
  pedestrianPressed = true;
}
void setup() {
  Serial.begin(115200);
  pinMode(redLedPin, OUTPUT);
  pinMode(yellowLedPin, OUTPUT);
  pinMode(greenLedPin, OUTPUT);
  pinMode(blueLedPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(buttonPin), handleButtonPress, FALLING);
  digitalWrite(redLedPin, LOW);
  digitalWrite(yellowLedPin, LOW);
  digitalWrite(greenLedPin, LOW);
  digitalWrite(blueLedPin, LOW);
}
void loop(){
  if (pedestrianPressed) {
    
    Serial.println("Pedestrian button pressed!.");
    digitalWrite(blueLedPin, HIGH);
    delay(1000);    
   
    pedestrianPressed = false;
  } else {
   digitalWrite(redLedPin, HIGH);
   digitalWrite(blueLedPin, LOW);
    delay(1000);  
    digitalWrite(redLedPin, LOW);
    digitalWrite(yellowLedPin, HIGH);
    digitalWrite(blueLedPin, LOW);
    delay(1000);  
    digitalWrite(yellowLedPin, LOW);
    digitalWrite(greenLedPin, HIGH);
    digitalWrite(blueLedPin, LOW);
    delay(1000); 
    digitalWrite(greenLedPin, LOW);
  }
  delay(50);
 }