#define TRIGGER_PIN 12 
#define ECHO_PIN 13    
#define LED_PIN 2      
#define buzzer 4 

void setup() 
{
  Serial.begin(9600); 
  pinMode(TRIGGER_PIN, OUTPUT); 
  pinMode(ECHO_PIN, INPUT);     
  pinMode(LED_PIN, OUTPUT); 
  pinMode(buzzer, OUTPUT);    
}

void loop()
 {
  long duration, distance; 

 
  digitalWrite(TRIGGER_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIGGER_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIGGER_PIN, LOW);

   duration = pulseIn(ECHO_PIN, HIGH);
  
  distance = duration * 0.0343 / 2;

  
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  
  if (distance <= 50) {
    digitalWrite(LED_PIN, HIGH);
  } else {
    digitalWrite(LED_PIN, LOW);
  }
  

   if (distance <= 20) {
    digitalWrite(buzzer, HIGH);
  } else {
    digitalWrite(buzzer, LOW);
  }
  delay(500); 
}