const int LDR = 0;
const int led = 8;

int lightCal;
int lightVal;


void setup()
{
  // We'll set up the LED pin to be an output.
  pinMode(led, OUTPUT);
  lightCal = analogRead(LDR);

}


void loop()
{

  lightVal = analogRead(LDR);


  if (lightVal < lightCal - 50)
  {
    digitalWrite(8, HIGH);
  }

  else
  {
    digitalWrite(8, LOW);
  }

}