#include<Wire.h>
int ldr;
void setup(){
    Wire.begin(0x08);
    Serial.beign(9600);
    Wire.onReceive(receiveEvent);
    Wire.onRequest(sendData);
    pinMode(13,OUTPUT);
    digitalWrite(13,LOW);
}

void loop(){
    ldr=analogRead(A0);
    if(ldr<50){
        digitalWrite(13,HIGH);
    }
    else{
        digitalWrite(13,LOW);
    }
    Serial.print(ldr);
    delay(100);
}
void receiveEvent(int howMany){
    while(Wire.available()){
        c=Wire.read();
        digitalWrite(13,c);
    }
}

void sendData(){
    Wire.write(ldr);
}