int LDRpin = A0;
int LEDpin = 13;
int threshold=500;
void setup() {
  pinMode(LEDpin, OUTPUT);
  Serial.begin(9600);
}
void loop () {
  int lightLevel = analogRead(LDRpin);
  Serial.println(lightLevel);
  if (lightLevel<threshold){
    digitalWrite(LEDpin , HIGH);
  }
  else {
    digitalWrite(LEDpin,LOW);
  }
  delay(100);
}