@SuppressWarnings("unchecked")
	public FollowingGraph(String dir) {
		this.dir = dir;
		try {
			FileInputStream fin = new FileInputStream(dir);
			ObjectInputStream oos = new ObjectInputStream(fin);
			map = (TreeMap<Integer, UserFollowers>) oos.readObject();
			oos.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}