Get the keys in a SortedList in CSharp

using System; //from   ww  w.  java  2  s .c om
using System.Collections; 
 
class MainClass { 
  public static void Main() { 
    SortedList sl = new SortedList(); 
     
    sl.Add("a", "A"); 
    sl.Add("b", "B"); 
    sl.Add("c", "C"); 
    sl.Add("d", "D"); 
 
    foreach(string s in sl.Keys) {
      Console.WriteLine(s); 
    }
  }
}