mod = 10 ** 9 + 7

n = 205050

fact = [1] * (n + 1)
invfact = [1] * (n + 1)
for i in range(1, n):
    fact[i + 1] = ((i+1) * fact[i]) % mod
invfact[n] = pow(fact[n], mod - 2, mod)
for i in range(n - 1, -1, -1):
    invfact[i] = invfact[i + 1] * (i + 1) % mod

def comb(n, r):
    if n < 0 or r < 0 or n - r < 0:
        return 0
    return fact[n] * invfact[r] * invfact[n - r] % mod


N, K = map(int, input().split())
ans = comb(N - 1, K) * fact[K] * N
for i in range(1, N):
    ans += comb(N - 1, K) * fact[K] * i
    ans += comb(N - 2, K - 2) * fact[K] * pow(2, mod - 2, mod) * i
    ans %= mod
print(ans)