public synchronized int joinToLobby(Integer ID, ClientThread ct) {        
        Lobby l = lobbies.get(ID);        
        if(l == null) {
            return NOT_EXIST_OPT;
        }        
        if(l.addPlayer(ct)) {
            try {
                ct.gameID = ID;
                ct.sendToClient(Packet.getSuccessPacket());
                l.tryStart();
            } catch(Exception e) {}
            return OK_OPT;
        } else {
            return FULL_OPT;
        }
    }