#include <Wire.h> 
          byte own_address = 8;
          void setup() {
            Wire.begin(own_address); 

            
            Wire.onReceive(receiveEvent);
            pinMode(0, OUTPUT);
            digitalWrite(0, LOW);
          }
          void loop() {
          }
   
          void receiveEvent(int howMany) {
            while (Wire.available()) {
              char c = Wire.read();
              if(c=='G'){
                digitalWrite(0,HIGH);
              }
              else if(c=='K'){
                digitalWrite(0,LOW);
              }
            }
          }