interface Document {
    void open();
    void close();
}

class PdfDocument implements Document {
    public void open() {
        System.out.println("Opening PDF...");
    }
    public void close() {
        System.out.println("Closing PDF...");
    }
}

class WordDocument implements Document {
    public void open() {
        System.out.println("Opening Word...");
    }
    public void close() {
        System.out.println("Closing Word...");
    }
}

abstract class DocumentFactory {
    public abstract Document createDocument();

    public void process() {
        Document doc = createDocument();
        doc.open();
        // do work
        doc.close();
    }
}

class PdfFactory extends DocumentFactory {
    public Document createDocument() {
        return new PdfDocument();
    }
}

class WordFactory extends DocumentFactory {
    public Document createDocument() {
        return new WordDocument();
    }
}

public static void main(String[] args) {
    DocumentFactory factory = new PdfFactory();
    factory.process();
}