const int buzzer = 8;
const int pir = 9;

void setup() {
  // put your setup code here, to run once:
  pinMode(buzzer, OUTPUT);
  pinMode(pir, INPUT);
  tone(buzzer, 1000);
  delay(500);
  noTone(buzzer);

}

void loop() {
  // put your main code here, to run repeatedly:
  if (digitalRead(pir) == HIGH) {
    tone(buzzer, 1000);
    delay(100);
    noTone(buzzer);
    delay(100);
  }
  else {
    digitalWrite(LED_BUILTIN, HIGH);
    delay(50);
    digitalWrite(LED_BUILTIN, LOW);
    delay(2000);
  }
}