N,K = map(int,input().split())
if N == 1:
    print(0)
    exit()

MOD = 10 ** 9 + 7
fact = [1]*(N+1)
rfact = [1]*(N+1)
r = 1
for i in range(1, N+1):
    fact[i] = r = r * i % MOD
rfact[N] = r = pow(fact[N], -1, MOD)
for i in range(N, 0, -1):
    rfact[i-1] = r = r * i % MOD

# nCk (mod MOD) を求める
def comb(n, k):
    return fact[n] * rfact[k] * rfact[n-k] % MOD

def perm(n, k):
    return fact[n] * rfact[n-k] % MOD

ans = 0
if K < N:
    ans = (N*(N+1)//2 * perm(N-1,K)) % MOD
ans += N * (N-1) // 2 * comb(K,K-2) * perm(N-2,K-2)
ans %= MOD
print(ans)