int trig =13;
int echo = 12;
int led =5;
int buz=2;

void setup() {
  Serial.begin(9600);
 pinMode(trig, OUTPUT);
  pinMode(led, OUTPUT);
   pinMode(buz, OUTPUT);
    pinMode(echo, INPUT);
delay(100);
  // put your setup code here, to run once:

}

void loop() 
{
  
digitalWrite(trig, LOW);
delayMicroseconds(10);
digitalWrite(trig, HIGH);
delayMicroseconds(10);
digitalWrite(echo, HIGH);
digitalWrite(trig, LOW);
int duration=pulseIn(echo, HIGH);
int distance = (duration*0.034)/2;


if (distance<100);
{
  digitalWrite(buz, HIGH);
  digitalWrite(led, HIGH);
  Serial.println("ALERT");
  delay(100);
}
 else
{
  
   digitalWrite(buz, LOW);
  digitalWrite(led, LOW);
  Serial.println("SAFE");
  delay(100);
  
}

}