using System;

using System.Text;

public class Program

{

    public static void Main()

    {

        // string encoded = Convert.ToBase64String(Encoding.ASCII.GetBytes("53207525")).Replace("=", "").Replace("+", "-").Replace("/", "_");

        string[] tests = {"53207525", "53206793", "53207551", "53307660", "53308449", "53308944", "53309531"};

        foreach(string code in tests) {

            string enc = Convert.ToBase64String(Encoding.ASCII.GetBytes(code)).Replace("=", "").Replace("+", "-").Replace("/", "_");

            Console.WriteLine(code + " - " + enc);

        }

    }

}