PageCalculator

using System;
//75
namespace PageCalculator
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] input = Console.ReadLine().
                Split(new[] { ' ', ',' },
                StringSplitOptions.RemoveEmptyEntries);
            int wordsPerPage = int.Parse(Console.ReadLine());
            string keyWord = Console.ReadLine();

            string[,] matrix = FillMatrix(input, wordsPerPage);
            int page = IsPresent(matrix, keyWord);
            Console.WriteLine(page);

        }
        public static string[,] FillMatrix(string[] tokens, int words)
        {
            string[,] matrix = new string[tokens.Length / words, words];
            int iterator = 0;

            for (int row = 0; row < matrix.GetLength(0); row++)
            {
                for (int col = 0; col < matrix.GetLength(1); col++)
                {
                    matrix[row, col] = tokens[iterator++];
                }
            }
            return matrix;
        }
        public static int IsPresent(string[,] arr, string word)
        {
            bool isPresent = false;
            int index = 0;
            for (int row = 0; row < arr.GetLength(0); row++)
            {
                for (int col = 0; col < arr.GetLength(1); col++)
                {
                    string w = arr[row, col];
                    if (w == word)
                    {
                        isPresent = true;
                        index = row;
                    }
                }
            }
            if (isPresent)
            {
                return index + 1;
            }
            else
            {
                return -1;
            }
        }
    }
}