void setup() {
  // put your setup code here, to run once:
pinMode(A0, INPUT);
pinMode(7, OUTPUT);
Serial.begin(9600);// 9600 - freq baud rate
}

void loop() {
  // put your main code here, to run repeatedly:
int ldr_value=analogRead(A0);
Serial.println(ldr_value);
if(ldr_value>400){
  digitalWrite(7, HIGH);
}
else{
  digitalWrite(7, LOW);
}
delay(1000);
}
// LDR SENSOR - DEPENDS UPON LIGHT INTENSITY VCC - EITHER 3.3V OR 5V
// GND - ANY GND PIN , D0 - IN ANY DIGITAL PIN
//A0 - A0 TO A5 (ANY)