public boolean checkUsername(String username)
	{
		if (username.isEmpty())
			return false;
		for (char c : username.toLowerCase().toCharArray())
		{
			int tmp = c;
			if (!(tmp > 96 && tmp < 123) || tmp == 230 || tmp == 248
					|| tmp == 229) // Checking username letters
				return false;
		}
		return true;
	}