abstract class AncTree {

    abstract int size( /* AncTree this */ );
    
    abstract AncTree changeName( /* AncTree this, */ String name1, String name2 );
    
    
    
    
    static void testStuff() {
        // examples of the data
        AncTree unk = new Unknown();
        AncTree jackie = new Child( "Jackie", 1917, "brown", new Unknown(), new Unknown() );
        
        
        assert unk.size() == 0;    // size(unk)
        assert jackie.size() == 1;
        assert (new Child("Marge", 1956, "blue", jackie, unk)).size() == 2;
    }





}