protected void readCases(Document doc, ContextFreePumpingLemma pl)
    {
        NodeList caseNodes = doc.getDocumentElement().getElementsByTagName(CASE_NAME);
        for(int i = 0; i < caseNodes.getLength(); i++)
        {
            Node caseNode = caseNodes.item(i);
            if(caseNode.getNodeType() != Node.ELEMENT_NODE)
                continue;
            int u = Integer.parseInt(((Element)caseNode).getElementsByTagName(CASE_U_NAME).item(0).getTextContent());
            int v = Integer.parseInt(((Element)caseNode).getElementsByTagName(CASE_V_NAME).item(0).getTextContent());
            int x = Integer.parseInt(((Element)caseNode).getElementsByTagName(CASE_X_NAME).item(0).getTextContent());
            int y = Integer.parseInt(((Element)caseNode).getElementsByTagName(CASE_Y_NAME).item(0).getTextContent());
            int j = Integer.parseInt(((Element)caseNode).getElementsByTagName(CASE_I_NAME).item(0).getTextContent());
            pl.addCase(new int[]{u, v, x, y}, j);
        }
    }