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
