#include "bits/stdc++.h"
using namespace std;
#ifdef DEBUG
auto&operator<<(auto &o, pair<auto, auto> p) {o << "(" << p.first << ", " << p.second << ")"; return o;}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{"; for(auto e : x) o<<e<<", "; return o<<"}";}
#define debug(X) cerr << "["#X"]: " << X << '\n';
#else
#define cerr if(0)cout
#define debug(X) ;
#endif
using ll = long long;
#define all(v) (v).begin(), (v).end()
#define ssize(x) int(x.size())
#define fi first
#define se second
#define mp make_pair
#define eb emplace_back
const int mod = 1'000'000'007;
int add(int a, int b) {
a += b;
return a >= mod ? a-mod : a;
}
int sub(int a, int b) {
return add(a, mod-b);
}
int mul(int a, int b) {
return int(((ll)a*b)%mod);
}
int fpow(int a, int b) {
int res = 1;
while (b) {
if (b&1) {
res = mul(a, res);
b--;
}
a = mul(a, a);
b /= 2;
}
return res;
}
int inv(int x) {
return fpow(x, mod-2);
}
struct BinomCoeff {
vector<int> sil, inv_sil;
BinomCoeff(int n) {
sil.resize(n+1);
inv_sil.resize(n+1);
inv_sil[0] = sil[0] = 1;
for (int i = 1; i <= n; ++i) {
sil[i] = mul(sil[i-1], i);
inv_sil[i] = inv(sil[i]);
}
}
int operator()(int n, int k) {
return mul(sil[n], mul(inv_sil[k], inv_sil[n-k]));
}
};
int main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
int n, k;
cin >> n >> k;
BinomCoeff C(n+1);
k = n - k;
int res = 0;
for (int i = 0; i <= k; ++i) {
if (i%2)
res = sub(res, mul(C(n+1, i), fpow(k+1-i, n)));
else
res = add(res, mul(C(n+1, i), fpow(k+1-i, n)));
}
cout << res << '\n';
return 0;
}
