// Create an array to hold 15 buttons pins
const int buttonPins[15] = {2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 23, 25, 27};

void setup() {
  Serial.begin(9600);
  // Set each button pin as an input with pull up resistor
  for (int i = 0; i < 15; i++) {
    pinMode(buttonPins[i], INPUT_PULLUP);
  }

}

void loop() {
  // Loop over all buttons and if any button is pressed, print its pin number
  for (int i = 0; i < 15; i++) {
    if (digitalRead(buttonPins[i]) == LOW) { // Button pressed
      Serial.print("Button pressed on pin: ");
      Serial.println(buttonPins[i]);
      delay(200); // Debounce delay
    }
  }

}