int ratanie = 0;
int says = 0;

void setup() {

pinMode(2, INPUT_PULLUP);

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

Serial.begin(9600);

}

void ratadlo() {
  ratanie = ratanie + 1;
  says = 1;
}

void loop() {

if(says == 1) {
  Serial.println(ratanie);
  says = 0;
}

}