Sub set from SortedSet

 
using System;
using System.Collections;
using System.Collections.ObjectModel;
using System.Collections.Specialized;

using System.Collections.Generic;
using System.Linq;
using System.Reflection;
class Program
{
    static void Main()
    {
        var letters = new SortedSet<char>("the quick brown fox");
        foreach (char c in letters.GetViewBetween('f', 'j'))
            Console.Write(c);

    }
}