@Override
    public String toString() {
        if (meetings.size() == 0) {
            return "{}";
        }
        StringBuilder sb = new StringBuilder();
        sb.append(meetings.size());
        sb.append("\\{");
        for (Integer key : meetings.keySet()) {
            sb.append(key);
            sb.append(":");
            sb.append(meetings.get(key));
            sb.append(",");
        }
        sb.deleteCharAt(sb.length() - 1);
        sb.append(")");
        return sb.toString();
    }