import java.util.*;

class Unknown implements AncTree { 

  public int size( /* Unknown this */ ) {
    return 0;
    }
    
  public AncTree changeName( /* Unknown this, */ String name1, String name2 ) {
    return new Unknown();
    }
    
  public List<String> allNames( /* Unknown this */ ) {
    return new ArrayList<String>();
    }
    
  public String toString( /* Unknown this */ ) {
    return "new Unknown()";
    }
  }