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

//We are given a matrix of strings of size N x M. Sequences in the matrix we define as sets of several neighbour elements located on the same line, column or diagonal. Write a program that finds the longest sequence of equal strings in the matrix. Examples:

class FindTheLongestSequence
{
    static void Main()
    {
        List<string> resultList = new List<string>();
        List<string> currentList = new List<string>();

        var matrix = new string[,] {{"ha","fifi","ho","hi"}, {"fo","ha","hi","xx"},{"xxx", "ho", "ha","xx"}};

        for (int row = 0; row < matrix.GetLength(0); row++)
        {
            int index = 0;
            for (int col = 0; col < matrix.GetLength(1); col++)
            {
                //here matrix[row, col] is our starting position;

                for (int i = 0; i < matrix.GetLength(1) - col; i++) //check horizontally
                {
                    if (matrix[row, col + i] != matrix[row, col])
                    {
                        break;
                    }
                    currentList.Add(matrix[row, col]);
                    }
                if (currentList.Count > resultList.Count)
                {
                    resultList = currentList.ToList(); //this keeps our current identical sequence.
                }
                currentList.Clear();
                for (int i = 0; i < matrix.GetLength(0) - row; i++) // check vertically
                {
                    if (matrix[row + i, col] != matrix[row, col])
                    {
                        break;
                    }
                    currentList.Add(matrix[row, col]);
                }
                if (currentList.Count > resultList.Count)
                {
                    resultList = currentList.ToList();
                }
                currentList.Clear();
                while (row + index < matrix.GetLength(0) && col + index < matrix.GetLength(1) && matrix[row + index, col + index] == matrix[row,col]) //check left-right diagonal
                {
                    currentList.Add(matrix[row, col]);
                    index++;
                }
                if (currentList.Count > resultList.Count)
                {
                    resultList = currentList.ToList();
                }
                currentList.Clear();
                index = 0;
                while (row + index < matrix.GetLength(0) && col - index >= 0 && matrix[row + index, col - index] == matrix[row,col]) //check right-left giagonal
                {
                    currentList.Add(matrix[row, col]);
                    index++;
                }
                if (currentList.Count > resultList.Count)
                {
                    resultList = currentList.ToList();
                }
                currentList.Clear();
                index = 0;
            }
        }
        Console.WriteLine(string.Join(" ", resultList));
    }
}