Little C Loves 3 II
Description
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.
Input
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.
Output
Print one integer — the maximum number of chessmen Little C can place.
Samples
2 2
0
3 3
8
Note
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 $(1,1)(3,2)$, $(1,2)(3,3)$, $(2,1)(1,3)$, $(3,1)(2,3)$.