const int LDR = 4;
const int LED = 5;
const int BUZZER = 21;
// put function declarations here:


void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(LDR, INPUT);
  pinMode(LED, OUTPUT);
  pinMode(BUZZER, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  int LDRval = analogRead(LDR);
  Serial.println(LDRval);
  //delay(2);
  if(LDRval<=400){
    digitalWrite(LED, HIGH);  // if LDR senses darkness
    tone(BUZZER, 1000);  // 1KHz sound signal
  }
  else{
    digitalWrite(LED, LOW);  // if LDR senses light
    noTone(BUZZER);
  }
}

// put function definitions here: