import java.util.Hashtable;
import java.lang.String;
import java.rmi.server.UnicastRemoteObject;

class Service extends UnicastRemoteObject
   implements GetPut
   
 {   protected Hashtable d;
    public Service() throws java.rmi.RemoteException {
       d = new Hashtable();
       }
     public void isAt(String person, String location)
        throws java.rmi.RemoteException { 
            //debug
            System.out.println("<"+person+','+location+">");
               synchronized(d) {
                 d.remove(person);
                 d.put(person,location);
               }
             }
     public String whereIs(String person)
        throws java.rmi.RemoteException { 
            String answer=null;
            //debug
            System.out.println("<"+person+">");
            synchronized(d) {
               answer= (String)d.get(person);
            }
               return answer;
           }
  }