#include <iostream>

using namespace std;
typedef long long ll;
const int MAX = 100010;
ll inv[MAX],fact[MAX],fi[MAX],mod = 1000000007;

void inverse(){
	int i;
	inv[1] = 1;
	for(i=2;i<MAX;i++){
		inv[i] = mod - (mod/i)*inv[mod%i]%mod;
	}
	fact[0] = fi[0] = 1;
	for(i=1;i<MAX;i++){
		fact[i] = fact[i-1]*i%mod;
		fi[i] = (fi[i-1]*inv[i])%mod;
	}
}

ll npk(ll n,ll k){
	if(n<0 || k<0 || n<k) return 0;
	return fact[n]*fi[n - k]%mod;
}

ll nck(ll n, ll k){
	if(n<0 || k<0 || n<k) return 0;
	return fact[n]*fi[k]%mod*fi[n-k]%mod;
}

int main(){
	ll i,n,k,x = 0;
	cin >> n >> k;
	inverse();
	for(i=1;i<n;i++){
		(x += i*(npk(n - 1,k) + nck(n - 2,k - 2)*fact[k]%mod*(mod + 1)/2%mod)) %= mod;
	}
	(x += n*(npk(n - 1,k))) %= mod;
	cout << x << endl;
}