int tiger=2;
int echo=3;
int a=12;
int detection=5;
int Duration,Distance;
void setup()
{
  pinMode(tiger,OUTPUT);
  pinMode(echo,INPUT);
  Serial.begin(9600);
  pinMode(a,OUTPUT);
}

void loop()
{
  digitalWrite(tiger,HIGH);
  delayMicroseconds(1000);
  digitalWrite(tiger,LOW);
  Duration=pulseIn(echo,HIGH);
  Distance=random(10);
  Serial.print("cm=");
  Serial.println(Distance);
  delay(0);
  if (Distance<detection)
  {
   digitalWrite(a,HIGH);
  } 
  else { 
    digitalWrite(a,LOW);
  } 

  delay(500); 
}