int trigPin = 11;
int echoPin = 12;
int LEDPin = 13;
long duration, cm, inches;

void setup() {

 
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(LEDPin, OUTPUT);
}

void loop() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(5);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  pinMode(echoPin, INPUT);
  duration = pulseIn(echoPin, HIGH);

  cm = (duration/2) / 29.1;
  inches = (duration/2) / 74;

  

  if (cm < 100)
  {

    digitalWrite(LEDPin, LOW);
  }
  else {

    
    digitalWrite(LEDPin, HIGH);


    
  }
}