传说HMH大沙漠中有一个M*N迷宫，里面藏有许多宝物。某天，Dr.Kong找到了迷宫的地图，他发现迷宫内处处有宝物，最珍贵的宝物就藏在右下角，迷宫的进出口在左上角。当然，迷宫中的通路不是平坦的，到处都是陷阱。Dr.Kong决定让他的机器人卡多去探险。

但机器人卡多从左上角走到右下角时，只会向下走或者向右走。从右下角往回走到左上角时，只会向上走或者向左走，而且卡多不走回头路。（即：一个点最多经过一次）。当然卡多顺手也拿走沿路的每个宝物。

Dr.Kong希望他的机器人卡多尽量多地带出宝物。请你编写程序，帮助Dr.Kong计算一下，卡多最多能带出多少宝物。

-HMH Desert legend has a M* N maze, there are many hidden treasures. One day, Dr.Kong found a map of the maze, the maze everywhere he found treasures, the most precious treasure is hidden in the bottom right corner of the maze of import and export in the upper left corner. Of course, the maze path is not flat, full of traps. Dr.Kong decided to let his robot Caddo go on a safari. But robots Caddo went from the top left bottom right corner, only to go down or go right. Come from the lower right back left corner, only to go up or go left, and Caddo no turning back. (Ie: a point after a maximum). Of course, it took Caddo smoothly along each treasure. Dr.Kong hopes his robot Caddo bring out as many treasures. Please write a program to help Dr.Kong calculations, cards up to bring out many more treasures.