int trig =18;
  int echo=5;
  int led =19;

long duration,distance;
void setup() {
  // put your setup code here, to run once:

pinMode(led,OUTPUT);
pinMode(trig, OUTPUT);
pinMode(echo, INPUT);
}

void loop() {
  // put your main code here, to run repeatedly:

digitalWrite(trig, LOW);
delayMicroseconds(2);
digitalWrite(trig, HIGH);
delayMicroseconds(200);
digitalWrite(trig, LOW);
duration=pulseIn(echo,HIGH);
distance=(duration/2) / 29.1;
delay(10);

if(distance < 10)
digitalWrite(led, HIGH);
else
digitalWrite(led, LOW);
delay(10);
}