#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
const int MAX = 5e5 + 10;
const long long MAX2 = 11;
const long long MOD = 1000000007;
const long long MOD2 = 1000000006;
const long long INF = 2e18;
const int dr[] = {1, 0, -1, 0, 1, 1, -1, -1, 0};
const int dc[] = {0, 1, 0, -1, 1, -1, 1, -1, 0};
const double pi = acos(-1);
const double EPS = 1e-9;
const int block = 2000;
long long n, k, ans;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> k;
  ans = 1;
  for (int i = 2; i <= k; ++i) ans = (ans * k) % MOD;
  n -= k;
  for (int i = 1; i <= n; ++i) ans = (ans * n) % MOD;
  cout << ans << '\n';
  return 0;
}
