using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Validate strong password");

        int conditionsCount = 0;

        string password = "123";

        HashSet<char> specialCharacters = new HashSet<char>() { '.', '?', '=', '@', '_' };

        if (password.Any(char.IsLower) && //Lower case 

             password.Any(char.IsUpper) &&

             password.Any(char.IsDigit) &&

             password.Any(specialCharacters.Contains))

        {

          Console.WriteLine("Contraseña valida!!");

        }

        else

        {

            Console.WriteLine("Contraseña no cumple las condiciones");

        }

        /*

        if (password.Any(char.IsLower))

            conditionsCount++;

        if (password.Any(char.IsUpper))

            conditionsCount++;

        if (password.Any(char.IsDigit))

            conditionsCount++;

        if (password.Any(specialCharacters.Contains))

            conditionsCount++;

​

        if (conditionsCount >= 3)

        {

            Console.WriteLine("Contraseña valida!!");

        }*/

    }

}