#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <Keypad.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);

const int ROW_NUM = 4; 
const int COLUMN_NUM = 4;
char keys[ROW_NUM][COLUMN_NUM] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'},
};
byte pin_rows[ROW_NUM] = {32, 33, 25, 26};  
byte pin_column[COLUMN_NUM] = {27, 14, 12, 13};

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

const String password = "2222"; 
String inputPassword;

void setup() {
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("ENTER PASSWORD:");
  lcd.setCursor(0, 1);
}

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

  if (key) {
    if (key == '#') { 
      if (inputPassword == password) {
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("Password accepted");
        delay(2000); 
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("ENTER PASSWORD:");
      } else {
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("Incorrect password");
        delay(2000); 
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("ENTER PASSWORD:");
      }
      inputPassword = "";
      lcd.setCursor(0, 1);
      lcd.print(inputPassword);
    } else if (key == '*') { 
      if (inputPassword.length() > 0) {
        inputPassword.remove(inputPassword.length() - 1);
        lcd.setCursor(0, 1);
        lcd.print("                "); 
        lcd.setCursor(0, 1);
        lcd.print(inputPassword);
      }
    } else {
      inputPassword += key; 
      lcd.setCursor(0, 1);
      lcd.print("                "); 
      lcd.setCursor(0, 1);
      lcd.print(inputPassword);
    }
  }
}