const int trgpin=9;
const int echopin=10;

void setup() {
  Serial.begin(9600);
  // put your setup code here, to run once:
pinMode(trgpin, OUTPUT);
pinMode(echopin, INPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(trgpin, LOW);
delayMicroseconds(2);
digitalWrite(trgpin, HIGH);
delayMicroseconds(10);
float duration=pulseIn(echopin,HIGH,30000);
float distance=duration*0.0343/2;
delay(1000);
Serial.print("Distance: ");
Serial.println(distance);

}