#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

const int MOD = 1e9 + 7;

struct mint {
    int n;
    mint(int n_ = 0) : n(n_) {}
};

mint operator+(mint a, mint b) { a.n += b.n; if (a.n >= MOD) a.n -= MOD; return a; }
mint operator-(mint a, mint b) { a.n -= b.n; if (a.n < 0) a.n += MOD; return a; }
mint operator*(mint a, mint b) { return (long long)a.n * b.n % MOD; }
mint &operator+=(mint &a, mint b) { return a = a + b; }
mint &operator-=(mint &a, mint b) { return a = a - b; }
mint &operator*=(mint &a, mint b) { return a = a * b; }

mint modinv(mint n) {
  int a = n.n;
  int b = MOD;
  int s = 1;
  int t = 0;
  while (b != 0) {
    int q = a / b;
    a -= q * b;
    s -= q * t;
    swap(a, b);
    swap(s, t);
  }
  if (s < 0) s += MOD;
  return s;
}

mint operator/(mint a, mint b) { return a * modinv(b); }

mint F[202020] = {1, 1};
mint R[202020] = {1, 1};
mint I[202020] = {0, 1};

mint C(int n, int r) {
  if (n < 0 || r < 0 || n < r) return 0;
  return F[n] * R[n - r] * R[r];
}

mint P(int n, int r) {
  if (n < 0 || r < 0 || n < r) return 0;
  return F[n] * R[n - r];
}

void init() {
  for (int i = 2; i < 202020; i++) {
    I[i] = I[MOD % i] * (MOD - MOD / i);
    F[i] = F[i - 1] * i;
    R[i] = R[i - 1] * I[i];
  }
}

int main() {
  init();
  int N, K;
  cin >> N >> K;
  mint ans = 0;
  for (int i = 1; i <= N; i++) {
    mint p = 0;
    // not i
    // P(N-1,K) / P(N,K)
    p += P(N-1,K)/P(N,K);
    if (i < N) {
      p += P(N-2,K-2) * C(K,2) / P(N,K);
    }
    ans += i*p;
  }
  ans *= P(N,K);
  cout << ans.n << endl;
}