Removes elements that match the predicate from SortedSet in CSharp

using System;/*from  w ww. j  a  v a  2s.  c  o m*/
using System.Collections;
using System.Collections.Generic;
using System.IO;


class Program
{
    static void Main(string[] args)
    {
        SortedSet<string> set1 = new SortedSet<string>();
        set1.Add("a");
        set1.Add("b");
        set1.Add("d");
        set1.Add("d");
        
        SortedSet<string> set2 = new SortedSet<string>();
        set2.Add("a");
        set2.Add("b");
        set2.Add("c");
        set2.Add("d");

        set1.RemoveWhere(myFunc);        

        foreach (string s in set1)
        {
            Console.WriteLine(s);
        }


    }
    private static bool myFunc(string s)
    {
        if (s.ToLower().EndsWith("a") ||
            s.ToLower().EndsWith("b"))
        {
            return true;
        }
        else
        {
            return false;
        }
    }    
}