Save Walle#3257

Save Walle

1 second

128 megabytes

Very easy

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 $(e x, ey)$ (ex, ey) provided that the position $(x, y)$ can be reached only from the point $(x - 1, y)$ (x - 1, y) or $(x, y - 1)$ (x, y - 1), and must hold the conditions $x \geq y$ x \ge y and $x \cdot y$ x \cdot y is even.

Input

Two positive integers $e x, ey (1 \leq e x, ey \leq 100)$ ex, ey~(1 \le ex, ey \le 100).

Output

Print the number of ways modulo $1 0^{9} + 7$ 10^9 + 7.

Examples

Example 1

Loading

Example 2

Loading

Example 3

Loading

(e x, ey)

(x - 1, y)

(x, y - 1)

x \geq y

x \cdot y

e x, ey (1 \leq e x, ey \leq 100)

1 0^{9} + 7