public int addUser(String name, String password)
	{
		if (name.length() < 4 || name.length() > 10)
			return -1;
		if (password.length() < 2 || password.length() > 10)
			return -2;
		if (users.containsKey(name))
			return -3;
		users.put(name, new Trader(this, name, password));
		return 0;
	}