#include <Keypad.h>
#include <LiquidCrystal.h>

const byte ROWS = 4;
const byte COLS = 4;

char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};

byte rowPins[ROWS] = {9, 8, 7, 6};
byte colPins[COLS] = {5, 4, 3, 2};

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

LiquidCrystal lcd(13, 12, 11, 10, 1, 0, 5, 4, 3, 2);

char password[] = "1212";
char input_password[5];
int index = 0;
bool is_correct = false;

void setup() {
  lcd.begin(16, 2);
}

void loop() {
  char key = keypad.getKey();
  if (key != NO_KEY) {
    if (key == '#' || index == 4) {
      if (strcmp(input_password, password) == 0) {
        lcd.clear();
        lcd.print("on");
        digitalWrite(LED_BUILTIN, HIGH);
        is_correct = true;
      } else {
        lcd.clear();
        lcd.print("not correct");
        digitalWrite(LED_BUILTIN, LOW);
        is_correct = false;
      }
      delay(1000);
      lcd.clear();
      index = 0;
      memset(input_password, 0, sizeof(input_password));
    } else {
      input_password[index] = key;
      index++;
    }
  }
}