int Sensor_Value;

void setup()
{
Serial.begin(9600);
pinMode(A0, INPUT); // Declare the A0 as an input
}

void loop() {
Sensor_Value = analogRead(A0); //Reads the value from the sensor connected at A0 and stores it.
Serial.println("LDR value is :");
Serial.println(Sensor_Value); //Prints the value of LDR to Serial Monitor.
}