using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        string html = @"Someone just requested to change your  account's credentials. If this was you, click on the link below to reset them.\r\n\r\nhttps://foo.foo.foo/foo/foo/foo/login-actions/action-token?key=eyJhbGciOiJIUzI1NiIsInR5cCIgOiAiSldUIiwia2lkIiA6ICI0NDBjZTZkYS01NDVjLTRlNmUtYmNmYS03ZDM0ZDU1MTg0ZTgifQ.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&client_id=foo-foo&tab_id=6vbAxY003to\r\n\r\nThis link and code will expire within 5 Minuten.\r\n\r\nIf you don't want to reset your credentials, just ignore this message and nothing will be changed.\r\n";

        string pattern = @"https:\/\/(.+?)\\r";

        Regex r = new Regex(pattern, RegexOptions.IgnoreCase);

        Match urlMatch = r.Match(html);

        string url = urlMatch.Value;

        Console.WriteLine(url);

    }

}