int ldr=0;
int brightness;

void setup(){
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
  pinMode(A0, INPUT);
}
void loop(){
  ldr=analogRead(A0);
  brightness=map(ldr, 0 , 1023, 0, 255);

  if(brightness<=150){
    digitalWrite(3, HIGH);
    digitalWrite(2, LOW);
    delay(100);
  }
  else{
    digitalWrite(2, HIGH);
    digitalWrite(3, LOW);
    delay(100);
  }
}