#include <bits/stdc++.h>   using namespace std;   int main() {     int n, k;     scanf( %d%d , &n, &k);     long long ans1 = 1, ans2 = 1;     for (int i = 1; i <= k - 1; i++) ans1 = ans1 * k % 1000000007;     for (int i = 1; i <= n - k; i++) ans2 = ans2 * (n - k) % 1000000007;     printf( %I64d n , ans1 * ans2 % 1000000007);     return 0;   }   