void setup() {
  Serial.begin(9600);
  pinMode(5, OUTPUT);   // Defining pin 5 as OUTPUT
  pinMode(6, INPUT);    // Defining pin 6 as INPUT
}

void loop() {
  digitalWrite(5, LOW);
  delayMicroseconds(5);
  
  digitalWrite(5, HIGH);
  delayMicroseconds(15);
  digitalWrite(5, LOW);

  int a = pulseIn(6, HIGH);  // Reading pulse duration
  float d = a * 0.0343 / 2;  // Converting duration to distance in cm

  Serial.println(d);         // Printing the distance
  delay(100);                // Small delay to make output more readable
}