using System;

public class Program

{

    public static string Base64Encode(string plainText) {

        var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(plainText);

        return System.Convert.ToBase64String(plainTextBytes);

    }

    public static string Base64Decode(string base64EncodedData) {

        var base64EncodedBytes = System.Convert.FromBase64String(base64EncodedData);

        return System.Text.Encoding.UTF8.GetString(base64EncodedBytes);

    }

    public static void Main()

    {

        string test = Base64Encode("laci");

        Console.WriteLine(test);

        string encoded = Base64Decode(test);

        Console.WriteLine(encoded);

    }

}