### Bricks

Time Limit: 1000 ms Memory Limit: 32768 KiB

#### Problem Description

Little White bought a new house recently. She doesn't like the design of the floor anyway, so she decides to decorate the floor. Now she has bricks of the 5 shapes below, all with an infinite amount.

Bricks cannot overlap each other, and you cannot rotate them to fit in the "holes".
Now, please tell Little White how many units can she cover using these bricks.

#### Input

For every test case, you are given two integers n and m indicating the floor is an n*m rectangle consisting of n*m 1*1 grids.(1<=n<=100,1<=m<=6)
Proceed to the end of file.

#### Output

For every test case, print an integer on a single line, representing the maximum possible area that can be covered.

#### Sample Input

1 4
2 3
3 2
4 4

#### Sample Output

0
4
4
12

#### Hint

hdoj2442 有链接提示的题目请先去链接处提交程序，AC后提交到SDUTOJ中，以便查询存档。

#### Source

2008 Asia Harbin Regional Contest Online