void setup() 
{    Serial.begin(9600);
     pinMode(13,INPUT);
     pinMode(12,OUTPUT);
     pinMode(8,OUTPUT);
  
}

void loop() 
{   int time;
int distance;
 digitalWrite(12,LOW);
 delay(1000);
 digitalWrite(12,HIGH);
 delay(1000);
 digitalWrite(12,LOW);
 time=pulseIn(13,HIGH);
distance=time*0.0346/2;
Serial.println(distance);
if(distance<=100)
{digitalWrite(8, HIGH);
delay(1000);}
else
{digitalWrite(8,LOW);
delay(1000);}

}