const int Trigpin=4;
const int Echopin=2;
long duration;
int distance;


void setup()
{
  Serial.begin(9600);
  pinMode(Trigpin,OUTPUT);
  pinMode(Echopin,INPUT);
  pinMode( , OUTPUT);
  pinMode(, OUTPUT);
  pinMode(, OUTPUT);
}


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


  duration=pulseIn(Echopin,HIGH);
  distance=duration*0.034/2;
  Serial.print("Dist:");
  Serial.print(distance);
  Serial.println(" cm");
}

if (distance<100);
{
  digitalWrite(RLED, HIGH);
  digitalWrite(GLED, LOW);
  digitalWrite(BUZ, HIGH);
}
else
{
  digitalWrite(RLED, LOW);
  digitalWrite(GLED, HIGH);
  digitalWrite(BUZ, LOW);
 }
}