int button_1 =15;
int button_2 =2;

void setup() {

   Serial.begin(9600);
  //Initialize the digital pins as inputs
  pinMode(button_1, INPUT);
  pinMode(button_2, INPUT);

 
}

void loop() {
  //Read the states of push button values
  int buttonstate_1 = digitalRead(button_1);
  int buttonstate_2 = digitalRead(button_2);

  //active low
  if(buttonstate_1 == LOW){
    Serial.println("Button 1 is pressed");
    delay(500);
  }

  //active high
  if(buttonstate_2 == HIGH){
    Serial.println("Button 2 is pressed");
    delay(500);
  }
}