#include <bits/stdc++.h>
typedef long long ll;
typedef long double ld;
using namespace std;
#define F first
#define S second
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define SZ(x) (int)(x).size()
#define int ll
const int N = 1e5 + 10;
const int MOD = 1e9 + 7;
void add(int &a, int b) {
a += b;
if (a >= MOD) {
a -= MOD;
}
}
int mult(int a, int b) {
return (a * 1ll * b) % MOD;
}
int b_pow(int a, int b) {
if (!b) {
return 1;
}
if (b & 1) {
return mult(a, b_pow(a, b - 1));
}
return b_pow(mult(a, a), b >> 1);
}
int f[N], rf[N];
int C(int n, int k) {
if (k < 0 || k > n) {
return 0;
}
return mult(f[n], mult(rf[k], rf[n - k]));
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, m;
cin >> n >> m;
m = n - m;
f[0] = rf[0] = 1;
for (int i = 1; i <= n + 1; i++) {
f[i] = mult(f[i - 1], i);
rf[i] = b_pow(f[i], MOD - 2);
}
int ans = 0;
for (int k = 0; k <= m; k++) {
int vl = mult(C(n + 1, k), b_pow(m + 1 - k, n));
if (k & 1) {
vl = MOD - vl;
}
add(ans, vl);
}
cout << ans << '\n';
}
