import com.groupdocs.merger.Merger;
import com.groupdocs.merger.licensing.License;

public class MergePPTXfilesUsingJava {
    public static void main(String[] args)  throws Exception {

        // Set License to avoid the limitations of Merger library
        License license = new License();
        license.setLicense("GroupDocs.Merger.lic");

        // Load the source PPTX file
        Merger merger = new Merger("input.pptx");
        // Add another PPTX file to merge
        merger.join("input.pptx");
        // Merge PPTX files and save result
        merger.save("output.pptx");
    }
}