def comb(n, k, mod=10 ** 9 + 7):
    denominator = 1
    numerator = 1
    for i in range(1, k + 1):
        denominator = denominator * i % mod
    for i in range(n - k + 1, n + 1):
        numerator = numerator * i % mod
    return numerator * pow(denominator, mod - 2, mod) % mod


def main():
    boxes, colors = map(int, input().split())
    mod = 10 ** 9 + 7
    answer = 1
    for i in range(colors):
        answer = (answer * (boxes - i)) % mod
    denominator = 1
    for i in range(1, boxes - colors - 1):
        denominator = (denominator * i) % mod
    numerator = 1
    for i in range(colors + 1, boxes):
        numerator = (numerator * i) % mod
    answer = (answer * pow(denominator, mod - 2, mod) * numerator) % mod
    print(answer)


if __name__ == '__main__':
    main()