#include <Keypad.h> 
#define row_num 4
#define col_num 4
String password = "111111";
String input = "";
char keys[row_num][col_num] = {
  { '1', '2', '3', 'A' },
  { '4', '5', '6', 'B' },
  { '7', '8', '9', 'C' },
  { '*', '0', '#', 'D' }
};
byte row_pins[row_num]={19,18,5,17};
byte col_pins[col_num]={16,4,2,15};
Keypad keypad=Keypad(makeKeymap(keys),row_pins,col_pins,row_num,col_num);

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  Serial.println("Hello, ESP32!");
}

void loop() {
  char key=keypad.getKey();
  if(key){
    if(key=='#'){
      Serial.println();
      if(input.compareTo(password)==0){
        Serial.println("Access granted");
        while(true);
      }
      else{
        Serial.println("Access denied");
        Serial.print("Try again");
      }
      input="";
    }
  }
  // put your main code here, to run repeatedly:
  delay(10); // this speeds up the simulation
}