private void writeAchievements(OutputStream out, List<AchievementRecord> achievements) throws IOException {
		
		writeInt(out, achievements.size());
		
		for (AchievementRecord rec : achievements) {
			writeString(out, rec.getAchievementId());
			int diff = 0;
			switch(rec.getDifficulty()) {
				case NORMAL: diff = 1; break;
				case EASY: diff = 0; break;
			}
			writeInt(out, diff);
		}
		
	}