import java.io.IOException;
public interface ClientRef {
  public void confirm(int[][] card) throws IOException;
  public void deny(String reason) throws IOException;
  public void numberCalled(int number) throws IOException;
  public void forfeit() throws IOException;
  public void win(String winner) throws IOException;
}

import java.io.IOException;
public interface ServerRef{
  public void join(ClientRef client,String name,String session) throws IOException;
  public void bingo(ClientRef client) throws IOException;
}