long W = 1;

void setup() {
  pinMode(2, INPUT_PULLUP);

}

void loop() {
    if (digitalRead(2) == 0) {
      W = W * -1;
      if (W == -1) {
        pinMode(13, OUTPUT);
         digitalWrite(13, 1);
        delay(300);
      } else {
        pinMode(13, OUTPUT);
         digitalWrite(13, 0);
        delay(300);
      }
    }

}