@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		else if (obj == null)
			return false;
		else if (getClass() != obj.getClass())
			return false;
		else {
			Num other = (Num) obj;
			if (x == null && other.x != null)
				return false;
			else if (!x.equals(other.x))
				return false;
			else
				return true;
		}
	}