using System;

​

public class Program

{

    const string _ENVIRONMENT_ = "Preproduction";

    const string _REPLACEABLE_STRING_ = "cdiscount.com";

    public static void Main()

    {

        var uri = new Uri("https://order.cdiscount.com/hello");

        Console.WriteLine(uri.ToString());

        if(_ENVIRONMENT_ == "Preproduction"){

            uri = new Uri(uri.ToString().Replace(_REPLACEABLE_STRING_, "preprod-"+_REPLACEABLE_STRING_));

        }

        Console.WriteLine(uri.ToString());

    }

}