#define RED_LED_PIN 21
#define YELLOW_LED_PIN 22
#define GREEN_LED_PIN 23
#define BLUE_LED_PIN 19
#define SWITCH_PIN 18 
volatile bool pedestrianPressed = false;
void handleButtonPress() {
  pedestrianPressed = true;
}
void setup() {
  pinMode(RED_LED_PIN, OUTPUT);
  pinMode(YELLOW_LED_PIN, OUTPUT);
  pinMode(GREEN_LED_PIN, OUTPUT);
  pinMode(BLUE_LED_PIN, OUTPUT);
  pinMode(SWITCH_PIN, INPUT_PULLUP);
  digitalWrite(RED_LED_PIN, LOW);
  digitalWrite(YELLOW_LED_PIN, LOW);
  digitalWrite(GREEN_LED_PIN, LOW);
  digitalWrite(BLUE_LED_PIN, LOW);
   Serial.begin(115200);
   pinMode(SWITCH_PIN, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(SWITCH_PIN), handleButtonPress, FALLING);
}
void loop() {
  if (digitalRead(SWITCH_PIN) == HIGH) {
    digitalWrite(RED_LED_PIN, HIGH);
    digitalWrite(YELLOW_LED_PIN, LOW);
    digitalWrite(GREEN_LED_PIN, LOW);
     digitalWrite(BLUE_LED_PIN, LOW);
    delay(2000);  
    digitalWrite(RED_LED_PIN, LOW);
    digitalWrite(YELLOW_LED_PIN, HIGH);
    digitalWrite(GREEN_LED_PIN, LOW);
     digitalWrite(BLUE_LED_PIN, LOW);
    delay(2000);  
    digitalWrite(RED_LED_PIN, LOW);
    digitalWrite(YELLOW_LED_PIN, LOW);
    digitalWrite(GREEN_LED_PIN, HIGH);
     digitalWrite(BLUE_LED_PIN, LOW);
    delay(2000);
    digitalWrite(RED_LED_PIN, LOW);
    digitalWrite(YELLOW_LED_PIN, LOW);
    digitalWrite(GREEN_LED_PIN, LOW);
     digitalWrite(BLUE_LED_PIN, LOW);
    }
    if (pedestrianPressed,digitalRead(SWITCH_PIN) == LOW){
   
    digitalWrite(BLUE_LED_PIN, HIGH);
    digitalWrite(RED_LED_PIN, LOW);
    digitalWrite(YELLOW_LED_PIN, LOW);
    digitalWrite(GREEN_LED_PIN, LOW);
    pedestrianPressed = false;  
    }
  }