long duration, distance;
const int echoPin = 7;
const int trigPin = 8;

void setup()
{
 Serial.begin (9600);
 pinMode(trigPin, OUTPUT);
 pinMode(echoPin, INPUT);
 pinMode(13,OUTPUT);
 pinMode(12, OUTPUT);
 pinMode(11, OUTPUT);
}

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

 duration = pulseIn(echoPin, HIGH);
 distance = duration/57.8; // (cm)
 Serial.println(distance);

 delay(50);

  if (distance > 300);{
   digitalWrite(13,HIGH);
   digitalWrite(12,LOW);
   digitalWrite(11,LOW);
 }

 if (distance > 200 && distance <= 300);{
   digitalWrite(13,LOW);
   digitalWrite(12,HIGH);
   digitalWrite(11,LOW);
 }

 if(distance <= 200);{
   digitalWrite(13,LOW);
   digitalWrite(12,LOW);
   digitalWrite(11,HIGH);
 }

}