using System;
using System.Text.RegularExpressions;

public class Test
{
	public static string getReplacementNumber(int i)
        {
		return string.Format("<{0}>", i);
        }

	public static void Main()
	{
		string input = "abc foo abc bar abc";
		Regex rx = new Regex("abc");
		int i = 0;
		string result = rx.Replace(input, match => { return getReplacementNumber(i++); });
		Console.WriteLine(result);
	}
}