using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        var regex = new Regex("^NTL_XML_INS_[/d]{8}_NEW_[/d]{1.}.txt");

        var matchCollection = regex.Match("NTL_XML_INS_15072021_NEW_1.txt");

         Console.WriteLine(matchCollection.Success);

    }

}