using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;

public class Test
{
	public static void Main()
	{
		var text = "ABC_BC_BE08_C1000004_0124";
		var result = Regex.Matches(text, @"(?<=^(?:[^_]*_){2,})[^_]+").Cast<Match>().Select(x => x.Value);
    	foreach (var s in result)
        	Console.WriteLine(s);
	}
}