public boolean modificaSimptoma(String nom, List<String> dnis, List<String> malalties) {
        SortedSet<Simptoma> s = consultaSimptomes(nom, nom);
        if (s.isEmpty()) {
            return false;
        }
        Simptoma simptoma = s.first();
        for (String dni : dnis) {
            if (dni.charAt(0) == '+') {
                simptoma.afegirPacient(controladorPacients.getPacient(dni.substring(1).trim()));
            }
            if (dni.charAt(0) == '-') {
                simptoma.esborrarPacient(controladorPacients.getPacient(dni.substring(1).trim()));
            }
        }
        for (String malaltia : malalties) {
            if (malaltia.charAt(0) == '+') {
                simptoma.afegirMalaltia(consultaMalalties(malaltia.substring(1), malaltia.substring(1)).first());
            }

            if (malaltia.charAt(0) == '-') {
                simptoma.esborrarMalaltia(consultaMalalties(malaltia.substring(1), malaltia.substring(1)).first());
            }
        }
        return true;
    }