const int trigPin = 30;
const int echoPin = 1;
const int buzz = 53;

void setup() {
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode(buzz, OUTPUT);
Serial.begin(9600);
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);

long duration=pulseIn(echoPin, HIGH);
int distance= duration * 0.034/ 2;

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

if (distance <= 100) {
    digitalWrite(buzz, HIGH);
    delay(100);
    digitalWrite(buzz, LOW);
    delay(100);
   }
}