using System;
using System.Text.RegularExpressions;

class Test {
    static void Main() {
        string filename = "Try123_Enrollment_20130102_1200.xml";
        Regex pattern = new Regex(@"^[A-Za-z0-9]+_Enrollment_[0-9]{8}_[0-9]{4}\.xml$");
        if (pattern.IsMatch(filename))
        {
            Console.WriteLine("Matched");
        }
    }
}