Hamilton Pipeline

The city is a rectangle Namhetten m×n, consisting of square blocks.

Hamilton, an engineer wants to build in the city water supply, which is a closed pipe passing under each of the blocks exactly once.

Under each quarter of the pipe can either go straight or bent at 90 degrees.

As there are plans for Hamilton pipeline?

For example, for a city the size of 4×4 there are 6 plans for:

Input

In the input file contains the numbers m and n - the size of Namhetten (1 ≤ m×n ≤ 100).

Output

Bring out one number - the number of plans Hamilton plumbing, feasible in this city.

Examples