#include <Keypad.h>
const int rowmo=4;
const int colno=4;
char keys[rowmo][colno]={{'1','2','3','A'},{'4','5','6','B'},{'7','8','9','C'},{'*','0','#','D'}};
byte rowpin[rowmo]={9,8,7,6};
byte colpin[colno]={5,4,3,2};
Keypad keypad1=Keypad(makeKeymap(keys),rowpin,colpin,rowmo,colno);
const String password="2003";
String input_password="";
#define led 10
void setup()
{
  Serial.begin(9600);
  pinMode(led,OUTPUT);
  input_password.reserve(100);
  // put your setup code here, to run once:

}

void loop() 
{
  char key=keypad1.getKey();
  digitalWrite(led,1);
  if(key!=NO_KEY)
    {
      if(key=='0'||key=='1'||key=='2'||key=='3'||key=='4'||key=='5'||key=='6'||key=='7'||
      key=='8'||key=='9')
        {
          input_password+=key;
        }
      else input_password="";
      if(password==input_password)
        {
          Serial.println("correct password");
          digitalWrite(led,0);
          delay(10000);
          input_password="";
        }
      else
        digitalWrite(led,1);
    }
  /*char key=keypad1.getKey();
  //if(key!=NO_KEY)
    {
      Serial.println(key);
    }*/
  // put your main code here, to run repeatedly:

}