using System;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        // Input string.

        string[] markets = {"en-us", "ja-jp", "345678", "ja-jp select , (select)"};

        // Get a collection of matches.

        for (int i = 0; i < markets.Length; i++)

        {

            Match m = Regex.Match(markets[i],  @"[^\w\.@-]" , RegexOptions.IgnoreCase);

            if (m.Success)

                Console.WriteLine(markets[i]);

        }

    }

}