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

public class Test
{
	public static void Main()
	{
		var s = "f20s30t";
		var m = Regex.Match(s, @"^([fst])(\d+[fst])*$");
		if (m.Success)
		{
			Console.WriteLine(m.Groups[1].Value);
			foreach (var g in m.Groups[2].Captures.Cast<Capture>().Select(t => t.Value))
				Console.WriteLine(g);
		}
	}
}