The Computer Club stickers that everyone has been looking forward to have finally arrived in the club room! But when the club members arrived in the room, they got a surprise. Since Hasan did not say when ordering the stickers that they wanted the stickers to be cut one by one, the one square unit sized stickers came in large pieces, uncut and with no gaps between them. Can you help community members figure out how much they need to cut to make the labels separate?

Input

You will be given the integers \(\mathbf{N}\) and \(\mathbf{M}\) in one line. \(\mathbf{N}\) is the width of the large piece, \(\mathbf{M}\) is the length of the large piece.

• \( 1 \leq \mathbf{N}, \mathbf{M} \leq 10^4 \)

Output

You are asked to print a single integer, the unit length required to cut the stickers.

Example

Input:

3 4

Output:

17

Explanation:

• Only the red lines need to be cut.