#include <Arduino.h>
#include <Wire.h>

volatile uint8_t receivedValue = 0;

void setup() {
  Wire.begin(0x42); 
  Wire.onReceive(receiveEvent);
  Wire.onRequest(requestEvent);
  Serial.begin(9600);
}

void loop() {
}

void receiveEvent(int howMany) {
  if (howMany > 0) {
    receivedValue = Wire.read(); 
    Serial.print("Received from master: ");
    Serial.println(receivedValue);
  }
}

void requestEvent() {
  uint8_t reply = (receivedValue > 100) ? 2 : 4;
  Wire.write(reply);
  Serial.print("Sent to master: ");
  Serial.println(reply);
}