using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        Outer outer1 = new Outer();

        outer1.Name = "1";

        outer1.Inner.Add(new Inner { Name = "1.1" });

        outer1.Inner.Add(new Inner { Name = "1.2" });

        Outer outer2 = new Outer();

        outer2.Name = "2";

        outer2.Inner.Add(new Inner { Name = "2.1" });

        outer2.Inner.Add(new Inner { Name = "2.2" });

        Outer outer3 = new Outer();

        outer3.Name = "3";

        outer3.Inner.Add(new Inner { Name = "3.1" });

        outer3.Inner.Add(new Inner { Name = "3.2" });

        outer3.Inner.Add(new Inner { Name = "3.3" });

        List<Outer> outer = new List<Outer> { outer1, outer2, outer3 };

        var combinations = GetCombinations(outer);

        foreach(var combination in combinations)

        {

            Console.WriteLine(string.Join(" ", combination.Select(x => x.Name)));

        }

    }

    public static IEnumerable<Inner[]> GetCombinations(List<Outer> input)

    {

        int[] factors = new int[input.Count + 1];

        factors[factors.Length - 1] = 1;

        for(int i = factors.Length - 2; i >= 0; i--)

        {

            factors[i] = factors[i+1] * input[i].Inner.Count;

        }

        int max = factors[0];

        for(int j = 0; j < max; j++)

        {

        Inner[] result = new Inner[input.Count];

        for(int i = 0; i < input.Count; i++)

        {

            result[i] = input[i].Inner[j / factors[i+1] % input[i].Inner.Count];

        }

        yield return result;

        }

    }

    public class Outer

    {

        public string Name {get;set;}

        public List<Inner> Inner {get;set;} = new List<Inner>();

    }

    public class Inner

    {

        public string Name {get;set;}

    }

}