void setup() {
Serial.begin(9600);
pinMode(12, OUTPUT);
pinMode(13, INPUT);
}

void loop() {
  //Off the triger sensor
  digitalWrite(12,0);
  delayMicroseconds(2);
  //turn ON the triger sensor
  digitalWrite(12, HIGH);
  delayMicroseconds(10);
  digitalWrite(12, LOW);
  //return the time in microsec, record by
  // echo sensor connected to pin 13
  int duration=pulseIn(13,1);
  int distance=(duration/2)*0.034;
  Serial.println(distance);

}