|Codeforces Round #511 (Div. 1)|
Little C loves number «3» very much. He loves all things about it.
Now he is playing a game on a chessboard of size $$$n \times m$$$. The cell in the $$$x$$$-th row and in the $$$y$$$-th column is called $$$(x,y)$$$. Initially, The chessboard is empty. Each time, he places two chessmen on two different empty cells, the Manhattan distance between which is exactly $$$3$$$. The Manhattan distance between two cells $$$(x_i,y_i)$$$ and $$$(x_j,y_j)$$$ is defined as $$$|x_i-x_j|+|y_i-y_j|$$$.
He want to place as many chessmen as possible on the chessboard. Please help him find the maximum number of chessmen he can place.
A single line contains two integers $$$n$$$ and $$$m$$$ ($$$1 \leq n,m \leq 10^9$$$) — the number of rows and the number of columns of the chessboard.
Print one integer — the maximum number of chessmen Little C can place.
In the first example, the Manhattan distance between any two cells is smaller than $$$3$$$, so the answer is $$$0$$$.
In the second example, a possible solution is $$$(1,1)(3,2)$$$, $$$(1,2)(3,3)$$$, $$$(2,1)(1,3)$$$, $$$(3,1)(2,3)$$$.