using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        Dictionary<string, int> map = new Dictionary<string, int>();

        String text = "zf3kabxcde224lkzf3mabxc51+crsdtzf3nab=";

        int patternLength = 3;

        for (int i = 0 ; i <= text.Length - patternLength; i++) {

            String currentPattern = text.Substring(i, patternLength);

            if(!map.Any(x => x.Key == currentPattern))

            {

                map.Add(currentPattern, 1);

            }

            else

            {

                map[currentPattern]++;

            }

        }

        foreach(var item in map)

        {

            Console.WriteLine(item.Key + " -> " + item.Value);

        }

    }

}