#include <bits/stdc++.h> // PLEASE
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair <int, int> pp;
#define MAXN 100005
#define MAXM 1005
#define MAXP 25
#define A first
#define B second
#define MP make_pair
#define PB push_back
const ll INF = 2e9+13;
const ll MOD = 1e9+7;
int N, K;
ll fac[MAXN]; ll ifa[MAXN];
ll mmul(ll a, ll b) { return (a*b)%MOD; }
ll madd(ll a, ll b) { return (a+b)%MOD; }
ll nck(ll n, ll k)
{
return mmul(fac[n], mmul(ifa[n-k], ifa[k]));
}
ll pmod(ll a, ll b)
{
ll ret = 1LL;
while(b) {
if(b & 1) ret = mmul(ret, a);
a = mmul(a, a);
b /= 2LL;
}
return ret;
}
ll euler(ll n, ll m)
{
ll ans = 0;
for(int k=0; k<=m+1; k++) {
ll add = nck(n+1, k);
add = mmul(add, pmod(m+1-k, n));
if(k%2) ans = madd(ans, MOD-add);
else ans = madd(ans, add);
}
return ans;
}
int main(void)
{
ios_base::sync_with_stdio(false);
cin.tie(0);
fac[0] = 1LL; ifa[0] = 1LL;
for(int i=1; i<MAXN; i++) {
fac[i] = mmul(fac[i-1], i);
ifa[i] = pmod(fac[i], MOD-2);
}
cin >> N >> K;
cout << euler(N, N-K) << endl;
}
