using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        List<string> stuff1 = new List<string>();

        List<string> stuff2 = new List<string>();

        List<string> stuff3 = new List<string>();

​

        List<string> otherStuff = new List<string>();

​

        stuff1.Add("a1");

        stuff1.Add("a2");

        stuff1.Add("a3");

        stuff1.Add("a4");

        stuff2.Add("b1");

        stuff2.Add("b2");

        stuff2.Add("b3");

        stuff2.Add("b4");

        stuff3.Add("c1");

        stuff3.Add("c2");

        stuff3.Add("c3");

        stuff3.Add("c4");

        otherStuff.Add("d1");

        otherStuff.Add("d2");

        List<List<List<string>>> first64 = new List<List<List<string>>>();

        List<List<string>> other8 = new List<List<string>>();

​

        foreach (var v1 in stuff1) {

            // Fill temporary 2d list.

            List<List<string>> list2d = new List<List<string>>();           

            foreach (var v2 in stuff2) {

                // Fill temporary 1d list.

                List<string> list1d = new List<string>();

                foreach(var v3 in stuff3) {

                    list1d.Add(v1 + v2 + v3);

                }

                // Add each 1d list to the temp 2d list.

                list2d.Add(list1d);

            }

            // Add each 2d list to the main 3d list.

            first64.Add(list2d);

​

            // Create another 1d list to hold second combinations.

            List<string> otherList1d = new List<string>();

            foreach(var otherV in otherStuff) {

                otherList1d.Add(v1 + otherV);

            }

            // Add second 1d list to second 2d list.

            other8.Add(otherList1d);

        }

​

        // Print first 64.

        for(var x = 0; x < first64.Count; x++) {

            for(var y = 0; y < first64[x].Count; y++) {

                for(var z = 0; z < first64[x][y].Count; z++) {

                    Console.WriteLine(first64[x][y][z]);

                }

            }

        }

        // Print other 8.

        for(var x = 0; x < first64.Count; x++) {

            for(var y2 = 0; y2 < other8[x].Count; y2++) {

                Console.WriteLine(other8[x][y2]);

            }

        }

    }

}