using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

class Program
{
	static void Main(string[] args)
	{
		var subsets = GetSubsets(new List<int> { 1, 2, 3 });
		foreach (var subset in subsets)
		{
			foreach (var item in subset)
			{
				Console.Write(item + " ");
			}
			Console.WriteLine();
		}
	}

	private static List<List<int>> GetSubsets(List<int> set)
	{
		List<List<int>> subset = new List<List<int>>();
		subset.Add(new List<int>());

		for (int i = 0; i < set.Count; i++)
		{
			List<List<int>> subsetTemp = DeepCopyListOfList(subset);

			for (int j = 0; j < subsetTemp.Count; j++)
			{
				subsetTemp[j].Add(set[i]);
			}

			var subsetTempCount = subsetTemp.Count;
			for (int j = 0; j < subsetTempCount; j++)
			{
				subset.Add(new List<int>(subsetTemp[j]));
			}
		}
		return subset;
	}

	private static List<List<int>> DeepCopyListOfList(List<List<int>> subset)
	{
		var ret = new List<List<int>>();
		foreach (var list in subset)
		{
			ret.Add(new List<int>(list));
		}
		return ret;
	}
}