int ldr=A0;
int value=0;
int led=3;
void setup(){
  pinMode(led, OUTPUT);
  Serial.begin(9600);
}
void loop(){
  value=analogRead(ldr);
  Serial.print("ldr value is: ");
  Serial.println(value);
  if(value<300){
    digitalWrite(led, LOW);
  }
  else{
    digitalWrite(led, HIGH);
  }
}