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Problems

Save Walle

Save Walle

Time limit 1 second
Memory limit 128 MiB

Robot Walle is located in the coordinate plane at (0, 0). Calculate the number of ways in which the Walle can get to the position (ex, ey) provided that the position (x, y) can be reached only from the point (x - 1, y) or (x, y - 1), and must hold the conditions x \ge y and x \cdot y is even.

Input data

Two positive integers ex, ey~(1 \le ex, ey \le 100).

Output data

Print the number of ways modulo 10^9 + 7.

Examples

Input example #1
2 2
Output example #1
1
Input example #2
6 2
Output example #2
3
Input example #3
8 8
Output example #3
14
Source The 2012 All-Ukrainian Collegiate Programming Contest Round I Training Contest 19 April 2012