public CalcGraphSize(File activeUsers) throws IOException {
		BufferedReader reader = new BufferedReader(new FileReader(activeUsers));
		String s;
		while ((s = reader.readLine()) != null) {
			set.add(Long.parseLong(s));
		}
		reader.close();
		System.out.println("active users: " + set.size());
		log.println("active users: " + set.size());
		log.flush();
	}