int const trigPin =10;
int const echoPin = 9;
int const buzzPin = 2;
void setup() 
{
  pinMode(trigPin,OUTPUT);
  pinMode(echoPin,INPUT);
  pinMode(buzzPin,OUTPUT);
  Serial.begin(9600);
}

void loop() 
{
  int duration, distance;
  digitalWrite(trigPin,HIGH);
  delay(1);
  digitalWrite(trigPin,LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = (duration/2)/29.1;
  if(distance <= 50 && distance >= 0)
  {
    digitalWrite(buzzPin,HIGH);
    delay(10);
  }
  else
  {
    digitalWrite(buzzPin,LOW);
    delay(10);
  }
  delay(60);
  Serial.print("The distance from obstacle in cm =  ");
  Serial.println( distance );

}