const int trig=18;
const int echo=4;
const int LED=26;
long duration;
int distance;
void setup() {
  pinMode(18,OUTPUT);
  pinMode(5,INPUT);
  pinMode(26,OUTPUT);
  Serial.begin(9600);

}

void loop() {
 digitalWrite(18,LOW);
 delayMicroseconds(2);
 digitalWrite(18,HIGH);
 delayMicroseconds(10);
 digitalWrite(18,LOW);
    duration=pulseIn(4,HIGH);
    distance=duration*0.034/2;
if(distance<=15){
    Serial.print("Distance to Obstacle is ");
    Serial.print(distance);
    Serial.println("100 cm.");
    digitalWrite(26,HIGH);
}   
else{
  Serial.println("No Obstacle detected.");
  digitalWrite(26,LOW);
}
 
}