Arduino program to interface buzzer with LDR and LED

Write Arduino program to interface buzzer with LDR and LED

void setup()
{
  Serial.begin(9600);
  pinMode(13,OUTPUT);
  pinMode(8,OUTPUT);
  pinMode(A0,INPUT);

}
void loop()
{
  	int signal;
  	signal=analogRead(A0);
  	Serial.println(signal);
  	if(signal>=400)
    {
  		tone(8,1000); 
      	digitalWrite(13,HIGH);
  		delay(100);
      	noTone(8);
      	digitalWrite(13,LOW);
      	delay(100);
      Serial.println("ALARM ACTIVATED");
    }  	
  	else
    {
      noTone(8);
      digitalWrite(13,LOW);
      Serial.println("ALARM DEACTIVATED");
    }
}

LDR : Light Dependent Resistor