const int pir = 11;
const int bzz = 10;
const int led = 9;
int cnt = 0;

void setup() {
  // put your setup code here, to run once:
  pinMode(pir, INPUT);
  pinMode(led, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  if (digitalRead(pir) == HIGH) {
    while (cnt <= 30) {
      digitalWrite(led, HIGH);
      tone(bzz, 1000);
      delay(400);
      noTone(bzz);
      delay(100);
      cnt++;
    }
  } else {
    noTone(bzz);
    digitalWrite(led, LOW);
    cnt = 0;
  }
  digitalWrite(LED_BUILTIN, HIGH);
  delay(100);
  digitalWrite(LED_BUILTIN, LOW);
}