using System;

using System.Text.RegularExpressions;

public class Program {

    public static void Main() {

        Regex regex = new Regex(@"^[a-z0-9\-.]+$");

        var testStrings = new[] {

            "example.com",

            "a",

            "1",

            "w3.org",

            "a.c.b.d",

            "experts-exchange.com",

            "xn--skoleglde-m3a.nu",

            "A",

            "aBc",

            "a_b",

            "a..b",

            ".",

            "-",

            "a.",

            ".a",

            "-a",

            "a-"

        };

        foreach (var testString in testStrings) {

            Match match = regex.Match(testString);

            if (match.Success) {

                Console.WriteLine($"Matches {testString}.");

            }

            else {

                Console.WriteLine($"Does not match {testString}.");

            }

        }

    }

}