#include <bits/stdc++.h>
using namespace std;
#define ll long long
const ll mod=1e9+7, nx=1e5+5;
ll n, k, res, f[nx];
ll binpow(ll a, ll b)
{
if (b==0) return 1;
ll tmp=binpow(a, b/2);
if (b%2) return (((tmp*tmp)%mod)*a)%mod;
else return (tmp*tmp)%mod;
}
int main()
{
cin.tie(NULL)->sync_with_stdio(false);
cin>>n>>k;
f[0]=1;
for (int i=1; i<=n+1; i++) f[i]=(f[i-1]*i)%mod;
//cout<<"debug "<<(f[4]*binpow(f[4], mod-2))%mod<<'\n';
k=n-k;
for (int i=0; i<=k; i++)
{
ll tmp=(((((binpow(k+1-i, n)*f[n+1])%mod)*binpow(f[i], mod-2))%mod)*binpow(f[n+1-i], mod-2)%mod);
if (i%2) tmp=((-tmp)+mod)%mod;
res=(res+tmp)%mod;
}
cout<<res;
}
