MOD = 10**9 + 7
max_a = 2 * 10**6  # Since M and N can be up to 1e6, a = M + N -1 can be up to 2e6 -1

# Precompute factorial and inverse factorial up to max_a
fact = [1] * (max_a + 1)
for i in range(1, max_a + 1):
    fact[i] = fact[i-1] * i % MOD

inv_fact = [1] * (max_a + 1)
inv_fact[max_a] = pow(fact[max_a], MOD - 2, MOD)
for i in range(max_a - 1, -1, -1):
    inv_fact[i] = inv_fact[i + 1] * (i + 1) % MOD

# Read input
N, M = map(int, input().split())

a = M + N - 1
if a < N:
    comb_val = 0
else:
    comb_val = fact[a] * inv_fact[N] % MOD
    comb_val = comb_val * inv_fact[a - N] % MOD

ans = (2 * comb_val - M) % MOD
print(ans)