using System;

​

public class Program

{

    public static void Main()

    {

        var longestSubstring = GetLongestUniqueSubstringLength("baseball");

        Console.WriteLine("Longest Substring: " + longestSubstring);

    }

​

    public static int GetLongestUniqueSubstringLength(string input)

    {

        var longestLength = 0;

        var substring = "";

        var currentLength = 0;

        for (int i = 0; i < input.Length; i++)

        {

            if (substring.Contains(input[i].ToString()))

            {

                substring = substring.Remove(0, substring.IndexOf(input[i]) + 1);

                substring = substring + input[i];

                currentLength = substring.Length;

            }

            else

            {

                substring = substring + input[i];

                currentLength++;

                if (currentLength > longestLength)

                {

                    longestLength = currentLength;

                }

            }

            Console.WriteLine("Substring: " + substring);

        }

​

        return longestLength;

    }

}