#include <Keypad.h> // kutubxona
const byte satr = 4; // 4 satr
const byte ustun = 4; // 4 ustun
char keys[satr][ustun] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}}; 
byte satrPins[satr] = {9, 8, 7, 6}; 
byte ustunPins[ustun] = {5, 4, 3, 2}; 
String kod = "";
Keypad keypad = Keypad( makeKeymap(keys), satrPins, ustunPins, satr, ustun );
void setup(){
  pinMode(11, OUTPUT); // zummer
  pinMode(12, OUTPUT); // qizil svetodiod
  pinMode(13, OUTPUT); // yashil svetodiod
  Serial.begin(9600);
}
void loop(){
  char key = keypad.getKey();
  if (key) {
      if(!(key == 'D')){
          kod += key;
          Serial.println(kod); }
      else{
          if(kod == "1234") 
            {digitalWrite(13, 1); 
             Serial.println("parol to'g'ri");
             delay(5000);
             digitalWrite(13, 0);}
          else {digitalWrite(12, 1);
               Serial.println("parol noto'g'ri");
               tone(11, 500);
               delay(1000);
               noTone(11);
               delay(1000);
               digitalWrite(12, 0);}
          kod = "";
    }}}