Не могу реализовать алгоритм с FileStream - C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Text;
using System.Threading.Tasks;
 
namespace К
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] Slova= { "привет","пока","ок","вет" };//Слова которые нужно найти в строке   
            string Stroka = "приветпока";//Строка
 
            List<int> Sostoyaniya = FindAllSostoyaniya(Stroka, Slova);
 
            int count = 3;
            foreach (var item in Sostoyaniya)
            {
                Console.WriteLine(" Слово " + Slova[count] + " начинается с " + item + " позиции. ");
                count--;
            }
            Console.ReadLine();
 
        }
        private const int Stroka = 20;
        private const int Alphavit = 32;
 
        private static int[] Out = new int[Stroka];
        private static int[] FF = new int[Stroka];
        private static int[,] GF = new int[Stroka, Alphavit];
 
        private static int Algoritm(string[] Words, char NizkiyChar = 'а', char NaibolshiyChar = 'я')
        {
            Out = Enumerable.Repeat(0, Out.Length).ToArray();
            FF = Enumerable.Repeat(-1, FF.Length).ToArray();
 
            for (int i = 0; i < Stroka; ++i)
            {
                for (int j = 0; j < Alphavit; ++j)
                {
                }
            }
 
            int Sostoyaniya = 1;
 
            for (int i = 0; i < Words.Length; ++i)
            {
                string KeyWord = Words[i];
                int StartSostoyanie = 0;
 
                for (int j = 0; j < KeyWord.Length; ++j)
                {
                    int c = KeyWord[j] - NizkiyChar;
 
                    if (GF[StartSostoyanie, c] == -1)
                    {
                        GF[StartSostoyanie, c] = Sostoyaniya++;
                    }
 
                    StartSostoyanie = GF[StartSostoyanie, c];
                }
 
                Out[StartSostoyanie] |= (1 << i);
            }
 
            for (int c = 0; c < Alphavit; c++)
            {
                if (GF[0, c] == -1)
                {
                    GF[0, c] = 0;
                }
            }
 
            List<int> q = new List<int>();
            for (int c = 0; c <= NaibolshiyChar - NizkiyChar; ++c)
            {
                if (GF[0, c] != -1 && GF[0, c] != 0)
                {
                    FF[GF[0, c]] = 0;
                    q.Add(GF[0, c]);
                }
            }
 
            while (Convert.ToBoolean(q.Count))
            {
                int Sostoyanie = q[0];
                q.RemoveAt(0);
 
                for (int c = 0; c <= NaibolshiyChar - NizkiyChar; ++c)
                {
                    if (GF[Sostoyanie, c] != -1)
                    {
                        int Otkaz = FF[Sostoyanie];
 
                        while (GF[Otkaz, c] == -1)
                        {
                            Otkaz = FF[Otkaz];
                        }
 
                        Otkaz = GF[Otkaz, c];
                        FF[GF[Sostoyanie, c]] = Otkaz;
                        Out[GF[Sostoyanie, c]] |= Out[Otkaz];
                        q.Add(GF[Sostoyanie, c]);
                    }
                }
            }
 
            return Sostoyaniya;
        }
 
        private static int FindNextSostoyaniya(int StartSostoyanie, char NextVvod, char NizkiyChar = 'а')
        {
            int Otvet = StartSostoyanie;
            int c = NextVvod - NizkiyChar;
 
            while (GF[Otvet, c] == -1)
            {
 
                Otvet = FF[Otvet];
            }
 
            return GF[Otvet, c];
        }
 
        public static List<int> FindAllSostoyaniya(string Text, string[] KeyWord, char NizkiyChar = 'а', char NaibolshiyChar = 'я')
        {
            Algoritm(KeyWord, NizkiyChar, NaibolshiyChar);
 
            int StartSostoyanie = 0;
            List<int> Value = new List<int>();
 
            for (int i = 0; i < Text.Length; ++i)
            {
                StartSostoyanie = FindNextSostoyaniya(StartSostoyanie, Text[i], NizkiyChar);
 
                if (Out[StartSostoyanie] == 0)
                    continue;
 
                for (int j = 0; j < KeyWord.Length;j++)
                {
                    if (Convert.ToBoolean(Out[StartSostoyanie] & (1 << j)))
                    {
                        Value.Insert(0, i - KeyWord[j].Length + 1);
                    }
                }
            }
            return Value;
        }
    }
}