using System;
using System.Collections.Generic;
using System.Globalization;
using System.Text;
using System.Text.RegularExpressions;
using System.Reflection;
publicclass MainClass{
publicstaticvoid Main(){
Regex r1 = new Regex(@"((abc)*)x(\1)");
string s1 = "abcabcabcxabc";
Console.WriteLine(r1.IsMatch(s1) + "..." + r1.Match(s1).Value);
}
}