#include <iostream>

constexpr int mod = 0x3b9aca07;
int qpow(long long p, int q = mod - 2) {
  int ans = 1;
  while (q != 0) {
    if ((q & 1) != 0) {
      ans = ans * p % mod;
    }
    p = p * p % mod, q >>= 1;
  }
  return ans;
}
int n, k;

int main() {
  std::cin.tie(nullptr)->sync_with_stdio(false);
  std::cin >> n >> k, --k;
  int C = 1;
  for (int i = 1; i <= n + 1; ++i) {
    C = 1LL * C * i % mod;
  }
  for (int i = 1; i <= k + 1; ++i) {
    C = 1LL * C * qpow(i) % mod;
  }
  for (int i = 1; i <= n - k; ++i) {
    C = 1LL * C * qpow(i) % mod;
  }
  int ans = 0;
  for (int i = 0; i <= n - k; ++i) {
    ans = (ans + 1LL * qpow(i, n) * qpow(mod - 1, n - i - k) % mod * C) % mod;
    C = 1LL * C * (n - i - k) % mod;
    C = 1LL * C * qpow(i + k + 2) % mod;
  }
  std::cout << ans << '\n';
  return 0;
}