Hexagon Mystery

Time Limit: 1 Second    Memory Limit: 32768 KB

Still another problem about hexagon where it is divided into diamonds. The blue lines have outlined the second row of the hexagon. Take the red lines on the second row a certain configuration, you are to tell how many configurations are possible on the m-th row of a side-n hexagon.

Input

There are multiple tests, each with two positive integer n (1 <= n <= 50) and m (1 <= m <= 2n). Input is terminated with end of file.

Output

One number for each test - the number of possible configurations.

Sample Input

1 1
2 2

Sample Output

2
10

Submit

Source: ZOJ Monthly, March 2003