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/Program.cs

using System;
using System.Text.RegularExpressions;
using System.Linq;
using System.Collections.Generic;
					
public class Program
{
	public static void Main()
	{
		var input = "{abc}@{defgh}mner{123}";
		var pattern = @"\{(.+?)\}";
		
		var matches = Regex.Matches(input, pattern);
		IList<string> output = matches.Cast<Match>().Select(x => x.Groups[0].Value).ToList();
			
		output.Dump();	
	}
}