int led1 = 11;
int led4 = 8;
int led3 = 5;
int led2 = 2;
int ldr = A0;
void setup() {
  Serial.begin(9600);
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);  
  pinMode(led3, OUTPUT);
  pinMode(led4, OUTPUT);  
  pinMode(ldr, OUTPUT);
  // put your setup code here, to run once:

}

void loop() {
  int a = analogRead(ldr);
  digitalWrite(ldr, HIGH);
  if (a < 500)
  {
    digitalWrite(led1, HIGH);
    digitalWrite(led2, HIGH);
    digitalWrite(led3, HIGH);
    digitalWrite(led4, HIGH);
    Serial.println("led on");
    delay(1000);
  }
  else 
  {
    digitalWrite(led1, LOW);
    digitalWrite(led2, LOW);
    digitalWrite(led3, LOW);
    digitalWrite(led4, LOW);
    Serial.println("led off");
    delay(1000);
  }
  // put your main code here, to run repeatedly:

}