int ldr=A0;
int led=8;
int a;
void setup() {
  // put your setup code here, to run once:
pinMode(ldr, INPUT);
pinMode(led, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
a=analogRead(ldr);
Serial.println(a);
if(a<300)
digitalWrite(led, HIGH);
else
digitalWrite(led, LOW);
}