using System;

using System.Collections.Generic;

public class Program

{

    public static int FindMaxLengthBetweenEqualCharacters(string s) {

        int maxLen = -1;

        var map = new Dictionary<char, int>();

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

        {

            if (!map.ContainsKey(s[i]))

            {

                map[s[i]] = i;

            }

            else 

            {

                maxLen = Math.Max(maxLen, i - map[s[i]] - 1);

            }

        }

​

        return maxLen;

    }

    public static void Main()

    {

        Console.WriteLine("UniLecs");

        // tests

        Console.WriteLine(FindMaxLengthBetweenEqualCharacters("abca").ToString()); // 2

        Console.WriteLine(FindMaxLengthBetweenEqualCharacters("abcaefghqwrta").ToString()); // 11

    }

}