#include <Keypad.h>

const int ROW_NUM = 4;
const int COLUMN_NUM = 3;
const int buzzer_pin = 10;

char keys[ROW_NUM][COLUMN_NUM] = {
  {'1','2','3'},
  {'4','5','6'},
  {'7','8','9'},
  {'*','0','#'}
};

byte pin_rows[ROW_NUM] = {8, 7, 6, 5};
byte pin_column[COLUMN_NUM] = {4, 3, 2};

Keypad keypad = Keypad( makeKeymap(keys), pin_rows, pin_column, ROW_NUM, COLUMN_NUM );

const String password = "1234"; 
String input_password;

void setup(){
  Serial.begin(9600);
  pinMode(buzzer_pin, OUTPUT);
  input_password.reserve(32); 

}

void loop(){
  char key = keypad.getKey();

  if (key){
    Serial.println(key);

    if(key == '*') {
      input_password = "";
    } else if(key == '#') {
      if(password == input_password) {
        Serial.println("password is correct");

      } else {
        Serial.println("password is incorrect, try again");
        
      }

      input_password = "";
    } else {
      input_password += key;
    }
  }
}