using System;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("SubStrings: " + count("subsequence", "sue"));

    }

    public static int count(String str, String pattern)

    {

        return countHelper(str, pattern, 0, 0);

    }

​

    public static int countHelper(String str, String pattern, int str_index, int pattern_index)

    {

        int count = 0;

        if (str_index <= str.Length - pattern.Length + pattern_index)

        {

            if (str[str_index] == pattern[pattern_index])

            {

                Console.WriteLine(str_index.ToString() +", "+ pattern_index.ToString() + "\n");

                if (pattern_index == pattern.Length - 1)

                {

                    count++;

                    count += countHelper(str, pattern, str_index + 1, pattern_index);

                }

                else

                {

                    count += countHelper(str, pattern, str_index + 1, pattern_index);

                    count += countHelper(str, pattern, str_index + 1, pattern_index + 1);

                }

            }

            else

            {

                count += countHelper(str, pattern, str_index + 1, pattern_index);

            }

        }

        return count;

    }

}