The turtle is located in the upper-left corner (1, 1) of the table of size 1012421 × 1099921. The animal is able only to walk one cell down or one cell right.

In how many ways the turtle can reach the cell (n, m)?

Input

Two integers n and m (1 ≤ n, m ≤ 50) are given in one line.

Output

Print one line – the number of ways to reach the cell (n, m).