#include <bits/stdc++.h>
const int mod = 1000000007;
int k, w;
int fac[1000010];
int invfac[1000010];
inline int gcd(int a, int b, int &x, int &y) {
  if (b == 0) {
    x = 1;
    y = 0;
    return a;
  }
  int d = gcd(b, a % b, x, y);
  int t = x;
  x = y;
  y = t - a / b * y;
  return d;
}
inline int inv(int a) {
  int x, y, d = gcd(a, -mod, x, y);
  return ((long long)x * d % mod + mod) % mod;
}
inline int perm(int a, int b) {
  if (b > a || b < 0) return 0;
  return (long long)fac[a] * invfac[a - b] % mod;
}
inline int pow(int a, int b) {
  int g = 1;
  for (; b; b >>= 1) {
    if (b & 1) g = (long long)g * a % mod;
    a = (long long)a * a % mod;
  }
  return g;
}
void predo() {
  fac[0] = 1;
  for (int i = 1; i <= k; i++) fac[i] = (long long)fac[i - 1] * i % mod;
  invfac[k] = inv(fac[k]);
  for (int i = k - 1; i >= 0; i--)
    invfac[i] = (long long)invfac[i + 1] * (i + 1) % mod;
}
int solve() {
  int maxl = k + w, minl = w + 1;
  int ans = 0;
  predo();
  for (int l = minl; l <= maxl; l++) {
    int tmp;
    if (w * 2 > l + 1) {
      int sl = l - w;
      int midl = 2 * w - l;
      tmp = (long long)perm(k, sl) * perm(k, sl) % mod * pow(k, midl - 2) %
            mod *
            ((long long)k * k % mod - (long long)(k - sl) * (k - sl) % mod +
             mod) %
            mod;
    } else if (w * 2 == l + 1) {
      int sl = w - 1;
      int midl = 1;
      tmp = (long long)k *
            ((long long)perm(k, sl) * perm(k, sl) % mod -
             (long long)perm(k - 1, sl) * perm(k - 1, sl) % mod + mod) %
            mod;
    } else {
      int sl = w;
      int midl = l - 2 * w;
      int k2 = k - midl;
      tmp =
          ((long long)perm(k, midl) * perm(k2, sl) % mod * perm(k2, sl) % mod -
           (long long)perm(k, midl + 2) * perm(k2 - 2, sl - 1) % mod *
               perm(k2 - 2, sl - 1) % mod +
           mod) %
          mod;
    }
    ans = (ans + tmp) % mod;
  }
  return ans;
}
int main() {
  scanf("%d %d\n", &k, &w);
  printf("%d\n", solve());
  return 0;
}
