@Override
    public void actionPerformed(ActionEvent e) 
    {
        if (e.getSource() == load)
            try {
            loadFile();
        } catch (FileNotFoundException ex) {
            System.out.println("File not found: " + ex.getMessage());
        } catch (IOException ex) {
            System.out.println("General I/O exception: " + ex.getMessage());
        }
        if (e.getSource() == solve)
            startSolver();    
    }