import math
mod = int(1e9 + 7)
s = input().split();
x = int(s [0])
y = int(s [1])
n = x + y - 2
k = y - 1
ans = 1.0
for i in range (1, n + 1):
    ans *= i;
    if i <= k:
        ans /= i
    if i <= n - k:
        ans /= i;
print(round(ans) % mod)