using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
 
public class Test
{
	public static void Main()
	{
		var pattern = @"^[^_]*_[^_]*(?:_([^_]+))+";
        var str = "ABC_BC_BE08_C1000004_0124";
        var strings = Regex.Match(str, pattern).Groups[1].Captures.Select(c => c.Value);
 
        foreach (String s in strings)
        {
            Console.WriteLine(s);
        }
	}
}

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