const int trigPin = 9;  
const int echoPin = 10; 

long duration; 
int distance;

void setup() {  
  pinMode(trigPin, OUTPUT);  
  pinMode(echoPin, INPUT);  
  Serial.begin(9600);  
}

void loop() {  
  digitalWrite(trigPin, LOW);  
  delayMicroseconds(2);  
  digitalWrite(trigPin, HIGH); 
  delayMicroseconds(10);  
  digitalWrite(trigPin, LOW);  

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

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

  delay(500);
}