beaver

using System;
using System.Collections.Generic;
using System.Linq;

namespace _02.BeaverAtWork
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            char[,] matrix = new char[n, n];
            int beaverRow = -1;
            int beaverCol = -1;
            int woodBranchesCount = 0;
            Stack<char> woodBranches = new Stack<char>();

            for (int row = 0; row < n; row++)
            {
                char[] colElements = Console.ReadLine().Split(" ", StringSplitOptions.RemoveEmptyEntries).Select(char.Parse).ToArray();
                for (int col = 0; col < n; col++)
                {
                    matrix[row, col] = colElements[col];
                    if (matrix[row, col] == 'B')
                    {
                        beaverRow = row;
                        beaverCol = col;
                    }
                    if (Char.IsLower(matrix[row, col]))
                    {
                        woodBranchesCount++;
                    }
                }
            }
            string command = Console.ReadLine();
            while (command != "end")
            {

                switch (command)
                {
                    case "up":
                        matrix[beaverRow, beaverCol] = '-';
                        beaverRow--;
                        if (!IsInside(matrix, beaverRow, beaverCol))
                        {
                            beaverRow++;
                            matrix[beaverRow, beaverCol] = 'B';
                            if (woodBranches.Any())
                            {
                                woodBranches.Pop();
                            }
                        }
                        else
                        {
                            if (Char.IsLower(matrix[beaverRow, beaverCol]))
                            {
                                woodBranches.Push(matrix[beaverRow, beaverCol]);
                                woodBranchesCount--;
                                matrix[beaverRow, beaverCol] = 'B';
                            }
                            else if (matrix[beaverRow, beaverCol] == 'F')
                            {
                                matrix[beaverRow, beaverCol] = '-';
                                if (beaverRow != 0)
                                {
                                    beaverRow = 0;
                                }
                                else
                                {
                                    beaverRow = n - 1;
                                }
                                if (Char.IsLower(matrix[beaverRow, beaverCol]))
                                {
                                    woodBranches.Push(matrix[beaverRow, beaverCol]);
                                    woodBranchesCount--;
                                    matrix[beaverRow, beaverCol] = 'B';
                                }
                            }
                        }
                        break;
                    case "down":
                        matrix[beaverRow, beaverCol] = '-';
                        beaverRow++;
                        if (!IsInside(matrix, beaverRow, beaverCol))
                        {
                            beaverRow--;
                            matrix[beaverRow, beaverCol] = 'B';
                            if (woodBranches.Any())
                            {
                                woodBranches.Pop();
                            }
                        }
                        else
                        {
                            if (Char.IsLower(matrix[beaverRow, beaverCol]))
                            {
                                woodBranches.Push(matrix[beaverRow, beaverCol]);
                                woodBranchesCount--;
                                matrix[beaverRow, beaverCol] = 'B';
                            }
                            else if (matrix[beaverRow, beaverCol] == 'F')
                            {
                                matrix[beaverRow, beaverCol] = '-';
                                if (beaverRow != n - 1)
                                {
                                    beaverRow = n - 1;
                                }
                                else
                                {
                                    beaverRow = 0;
                                }
                                if (Char.IsLower(matrix[beaverRow, beaverCol]))
                                {
                                    woodBranches.Push(matrix[beaverRow, beaverCol]);
                                    woodBranchesCount--;
                                    matrix[beaverRow, beaverCol] = 'B';
                                }
                            }
                        }
                        break;
                    case "left":
                        matrix[beaverRow, beaverCol] = '-';
                        beaverCol--;
                        if (!IsInside(matrix, beaverRow, beaverCol))
                        {
                            beaverCol++;
                            matrix[beaverRow, beaverCol] = 'B';
                            if (woodBranches.Any())
                            {
                                woodBranches.Pop();
                            }
                        }
                        else
                        {
                            if (Char.IsLower(matrix[beaverRow, beaverCol]))
                            {
                                woodBranches.Push(matrix[beaverRow, beaverCol]);
                                woodBranchesCount--;
                                matrix[beaverRow, beaverCol] = 'B';
                            }
                            else if (matrix[beaverRow, beaverCol] == 'F')
                            {
                                matrix[beaverRow, beaverCol] = '-';
                                if (beaverCol != 0)
                                {
                                    beaverCol = 0;
                                }
                                else
                                {
                                    beaverCol = n - 1;
                                }
                                if (Char.IsLower(matrix[beaverRow, beaverCol]))
                                {
                                    woodBranches.Push(matrix[beaverRow, beaverCol]);
                                    woodBranchesCount--;
                                    matrix[beaverRow, beaverCol] = 'B';
                                }
                            }
                        }
                        break;
                    case "right":
                        matrix[beaverRow, beaverCol] = '-';
                        beaverCol++;
                        if (!IsInside(matrix, beaverRow, beaverCol))
                        {
                            beaverCol--;
                            matrix[beaverRow, beaverCol] = 'B';
                            if (woodBranches.Any())
                            {
                                woodBranches.Pop();
                            }
                        }
                        else
                        {
                            if (Char.IsLower(matrix[beaverRow, beaverCol]))
                            {
                                woodBranches.Push(matrix[beaverRow, beaverCol]);
                                woodBranchesCount--;
                                matrix[beaverRow, beaverCol] = 'B';
                            }
                            else if (matrix[beaverRow, beaverCol] == 'F')
                            {
                                matrix[beaverRow, beaverCol] = '-';
                                if (beaverCol != n - 1)
                                {
                                    beaverCol = n - 1;
                                }
                                else
                                {
                                    beaverCol = 0;
                                }
                                if (Char.IsLower(matrix[beaverRow, beaverCol]))
                                {
                                    woodBranches.Push(matrix[beaverRow, beaverCol]);
                                    woodBranchesCount--;
                                    matrix[beaverRow, beaverCol] = 'B';
                                }
                            }
                        }
                        break;
                }
                if (woodBranchesCount == 0)
                {
                    Stack<char> reversedWoodBranches = new Stack<char>();
                    while (woodBranches.Any())
                    {
                        reversedWoodBranches.Push(woodBranches.Pop());
                    }
                    Console.WriteLine($"The Beaver successfully collect {reversedWoodBranches.Count} wood branches: {string.Join(", ", reversedWoodBranches)}.");
                    PrintMatrix(matrix);
                    return;
                }
                command = Console.ReadLine();
            }
            Console.WriteLine($"The Beaver failed to collect every wood branch. There are {woodBranches.Count} branches left.");
            PrintMatrix(matrix);
        }

        private static bool IsInside(char[,] matrix, int row, int col)
        {
            return row >= 0 && row < matrix.GetLength(0) && col >= 0 && col < matrix.GetLength(1);
        }

        private static void PrintMatrix(char[,] matrix)
        {
            for (int row = 0; row < matrix.GetLength(0); row++)
            {
                for (int col = 0; col < matrix.GetLength(1); col++)
                {
                    Console.Write($"{matrix[row, col]} ");
                }
                Console.WriteLine();
            }
        }
    }
}