byte prev = 0;
byte now = 0;

void setup() {

  pinMode(2, INPUT_PULLUP);

attachInterrupt(digitalPinToInterrupt(2), zmena, CHANGE);

}

void zmena() {

  if(!(prev) && (PIND & 0b00000100)) {
    now = 1;
  }

  if((prev) && !(PIND & 0b00000100)) {
    now = 0;
  }

  prev = PIND & 0b00000100;

}

void loop() {

digitalWrite(13, now);

}