using System;

using System.Collections.Generic;

using System.Linq;

using System.Numerics;

public class Program

{

    static IEnumerable<int[]> BallsLocations(int boxCount, int ballCount) {

      BigInteger count = BigInteger.Pow(boxCount, ballCount);

​

      for (BigInteger i = 0; i < count; ++i) {

        int[] balls = new int[ballCount];

        int index = 0;

​

        for (BigInteger value = i; value > 0; value /= boxCount)

          balls[index++] = (int)(value % boxCount);

​

        yield return balls;

      }

    }

​

    static IEnumerable<string> BallsSolutions(int boxCount, int ballCount) {

      foreach (int[] balls in BallsLocations(boxCount, ballCount)) {

        List<int>[] boxes = Enumerable

          .Range(0, boxCount)

          .Select(_ => new List<int>())

          .ToArray();

​

        for (int j = 0; j < balls.Length; ++j)

          boxes[balls[j]].Add(j + 1);

​

        yield return string.Join(Environment.NewLine, boxes

          .Select((item, index) => $"Box {index + 1} : {string.Join(", ", item.Select(b => $"B{b}"))}"));

      }

    }

    public static void Main()

    {

      //TODO: put the right number of balls and boxes here  

      int balls = 3;

      int boxes = 2;

​

      string report = string.Join(

        Environment.NewLine + "------------------" + Environment.NewLine, 

        BallsSolutions(boxes, balls));

     Console.WriteLine(report);     

    }

}