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

public class Test
{
	public static void Main()
	{
    	var pattern = "^{(?:(?<c>[^{}]+)|(?<o>{)|(?<-o>}))*(?(o)(?!))}$";
    	var result = Regex.Matches("{a{bb{ccc{dd}}}}", pattern)
    	          .Cast<Match>().Select(p => p.Groups["c"].Captures)
    	          .ToList();
        foreach (var coll in result)
           foreach (var v in coll)
        	Console.WriteLine(v);
	}
}