public Tags(String filename) {
		tags = new ArrayList<String>();
		try {
			BufferedReader br = new BufferedReader(new FileReader(filename));
			String line = "";
			while ((line = br.readLine()) != null) {
				if (line.length() > 0) {
					String tag = line.substring(0, 1);
					// set type to IOB if there is at least on B-tag
					// furthermore assume the format to be consistent in its
					// type (IO vs. IOB)
					if (tag.equals("B"))
						type = "IOB";
					tags.add(line);
				}
			}
			br.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}