Longest Alphabetical Word

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

namespace LongestAlphabeticalWord
{
    class LongestAlphabeticalWord
    {
        static void Main(string[] args)
        {
            string tekst = Console.ReadLine();
            int number = int.Parse(Console.ReadLine());

            // buit the matrix //
            char[,] matrix = new char[number, number];
            int k = 0;
            int index = 0;
            for (int i = 0; i < number; i++)
            {
                for (int j = 0; j < number; j++)
                {
                    index = k % tekst.Length;
                    matrix[i, j] = (char)(tekst[index]);
                    k++;
                }
            }

            // check rows for longest word //

            string testString1 = "";
            string testString2 = "";
            string maxString1 = "";
            string maxString2 = "";
            for (int i = 0; i < number; i++)
            {
                for (int j = 0; j < number; j++)
                {
                    if (testString1 != matrix[i, j].ToString())
                    {
                        testString1 += matrix[i, j].ToString();
                    }


                    if (testString1.Length > maxString1.Length)
                    {
                        maxString1 = testString1;
                    }
                    else if ((testString1.Length == maxString1.Length) && (string.Compare(testString1,maxString1)==-1))
                    {
                        maxString1 = testString1;
                    }

                    if (j < number - 1 && matrix[i, j] > matrix[i, j + 1]) testString1 = "";

                    // columns for longest word//

                    if (testString2 != matrix[i, j].ToString())
                    {
                        testString2 += matrix[j, i].ToString();
                    }


                    if (testString2.Length > maxString2.Length)
                    {
                        maxString2 = testString2;
                    }
                    else if ((testString2.Length == maxString2.Length) && (string.Compare(testString2, maxString2) == -1))
                    {
                        maxString2 = testString2;
                    }

                    if (j < number - 1 && matrix[j, i] > matrix[j + 1, i]) testString2 = "";
                }
                testString1 = "";
                testString2 = "";
            }



            for (int i = number - 1; i >= 0; i--)
            {
                for (int j = number - 1; j >= 0; j--)
                {
                    if (testString1 != matrix[i, j].ToString())
                    {
                        testString1 += matrix[i, j].ToString();
                    }


                    if (testString1.Length > maxString1.Length)
                    {
                        maxString1 = testString1;
                    }
                    else if ((testString1.Length == maxString1.Length) && (string.Compare(testString1, maxString1) == -1))
                    {
                        maxString1 = testString1;
                    }

                    if (j >= 1 && matrix[i, j] > matrix[i, j - 1]) testString1 = "";

                    ////////////////////////////////////////////////////////////////////////////////
                    if (testString2 != matrix[i, j].ToString())
                    {
                        testString2 += matrix[j, i].ToString();
                    }


                    if (testString2.Length > maxString2.Length)
                    {
                        maxString2 = testString2;
                    }
                    else if ((testString2.Length == maxString2.Length) && (string.Compare(testString2, maxString2) == -1))
                    {
                        maxString2 = testString2;
                    }

                    if (j >= 1 && matrix[j, i] > matrix[j - 1, i]) testString2 = "";
                }
                testString1 = "";
                testString2 = "";
            }


            if (maxString1.Length > maxString2.Length) Console.WriteLine(maxString1);
            else Console.WriteLine(maxString2);
        }
    }
}