The city is a rectangle Namhetten \textbf{m}×\textbf{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 \textbf{90} degrees. As there are plans for Hamilton pipeline? For example, for a city the size of \textbf{4}×\textbf{4} there are \textbf{6} plans for: \includegraphics{https://static.e-olymp.com/content/a2/a2014a447095c9792f197c6b796306c2d77a1060.jpg} \InputFile In the input file contains the numbers \textbf{m} and \textbf{n} - the size of Namhetten (\textbf{1} ≤ \textbf{m}×\textbf{n} ≤ \textbf{100}). \OutputFile Bring out one number - the number of plans Hamilton plumbing, feasible in this city.