import java.util.ArrayList;
import java.util.Collections;
import java.util.Hashtable;
import java.util.List;
public class Main {
public static void main(String args[]) {
Hashtable h = new Hashtable();
h.put("a", "b");
h.put("c", "d");
h.put("e", "f");
for (String str : h.keySet()) {
System.out.println(str);
}
List v = new ArrayList(h.keySet());
Collections.sort(v);
for (String str : v) {
System.out.println(str + " " + (String) h.get(str));
}
}
}