// define pins 
int LEDs_pin [] = {11,12,13};
int btn_pin = 2;
int counter = 0;
int btnState = 0;

void btnPressed(){
  btnState = HIGH;
}

void setup() {
  // put your setup code here, to run once:
  // init pins
  // LEDs
  Serial.begin(9600);
  for (int i = 0 ; i <3 ; i++){
    pinMode(LEDs_pin[i], OUTPUT);

  }
  // init button 
  attachInterrupt(digitalPinToInterrupt(btn_pin), btnPressed, RISING);
  digitalWrite(LEDs_pin[0], HIGH);
}

void loop() {
  Serial.println(digitalPinToInterrupt(btn_pin));

  if (btnState == HIGH){
    digitalWrite(LEDs_pin[counter],LOW);
    counter = ((counter + 1) % 3) ;
    Serial.println(counter);
    digitalWrite(LEDs_pin[counter],HIGH);
    btnState=LOW;
  }
}