using System;

​

public class Program

{

    public static string ConvertToBase26(long number)

    {

        const int baseValue = 26;

        const string letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

        string result = string.Empty;

​

        while (number > 0)

        {

            int remainder = (int)(number % baseValue);

            result = letters[remainder] + result;

            number /= baseValue;

        }

​

        return result;

    }

    public static long ConvertFromBase26(string base26Number)

    {

        string base26 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

        long result = 0;

​

        for (int i = 0; i < base26Number.Length; i++)

        {

            char digit = base26Number[i];

            long value = base26.IndexOf(digit) + 1;

            result = result * 26 + value;

        }

​

        return result;

    }

    public static string ConvertToHexadecimal(long number)

    {

        return number.ToString("X");

    }

    public static long DecodeHexadecimal(string hexadecimal)

    {

        return long.Parse(hexadecimal, System.Globalization.NumberStyles.HexNumber);

    }

​

    public static void Main(string[] args)

    {

        long cnpj  = 999999999999; // Replace with your own number

        long cpf = 999999999; // Replace with your own number

        long data = 20231231; // Replace with your own number

        string h15cpf = ConvertToHexadecimal(cpf);

        string h26cpf = ConvertToBase26(cpf);

        Console.WriteLine("CPF  ORI: " + cpf);

        Console.WriteLine("CPF  HEX: " + h15cpf);

        Console.WriteLine("CPF  B26: " + h26cpf);

        Console.WriteLine("-----------------------------");

        string h15cnpj = ConvertToHexadecimal(cnpj);

        string h26cnpj = ConvertToBase26(cnpj);

        Console.WriteLine("CNPJ ORI: " + cnpj);

        Console.WriteLine("CNPJ HEX: " + h15cnpj);

        Console.WriteLine("CNPJ B26: " + h26cnpj);

        Console.WriteLine("-----------------------------");

        string h15data = ConvertToHexadecimal(data);

        string h26data = ConvertToBase26(data);

        Console.WriteLine("DATA ORI: " + data);

        Console.WriteLine("DATA HEX: " + h15data);

        Console.WriteLine("DATA B26: " + h26data);

        Console.WriteLine("-----------------------------");

    }

}

​