Problems
Save Walle
Save Walle
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 ≥ y and x * y is even.
Input
Two positive integers ex, ey (1 ≤ ex, ey ≤ 100).
Output
Print the number of ways modulo 1000000007.
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