const int LDRPin = A0;    
const int LEDPin = 13;    
const int threshold = 500; 

void setup() {
  pinMode(LDRPin, INPUT);  
  pinMode(LEDPin, OUTPUT); 
  Serial.begin(9600);     
}

void loop() {
  int LDRValue = analogRead(LDRPin); 
  Serial.println(LDRValue); 

  if (LDRValue < threshold) {
   
    digitalWrite(LEDPin, HIGH);
  } else {
   
    digitalWrite(LEDPin, LOW);
  }

  delay(100); 
}