C# SortedSet IntersectWith

public virtual void IntersectWith(
  IEnumerable<T> other
)

using System;//  w  w  w.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.IntersectWith(set2);

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


    }
}