#include<iostream>
#include<algorithm>
#include<vector>
#include<string>
#include<utility>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<functional>
#include<math.h>
#include<random>
#include <bitset>
using namespace std;
#define N (1000000000+7)
//#define N 998244353
#define INF 1e16
typedef long long ll;
typedef pair<int,int> P;
typedef pair<int,P> Q;

const int inf = (int)1e9; 

ll gcd(ll a, ll b) {
	if (b > a) {
		ll tmp = b;
		b = a;
		a = tmp;
	}
	if (a%b == 0)return b;
	else return gcd(b, a%b);
}

ll kaijo[200010];
void init() {
	kaijo[0] = 1;
	for (ll i = 1;i <= 200000;i++)kaijo[i] = (kaijo[i - 1] * i) % N;
}
 
ll inv(ll x,ll power) {
	ll res = 1;
	ll k = power;
	ll y = x;
	while (k) {
		if (k & 1)res = (res*y) % N;
		y = (y%N*y%N) % N;
		k /= 2;
	}
	return res;
}
 
ll Comb(ll n, ll k) {
	if (n < 0 || k < 0 || (n - k) < 0)return 0;
	ll b = kaijo[n];
	ll c = kaijo[n - k];
	ll d = kaijo[k];
	ll cd = (c*d) % N;
	return ((b%N)*(inv(cd,N-2)) % N) % N;
}

int main(void){
    ll n,k;
    cin>>n>>k;
    ll ans = 0;
    init();
    if(k==1){
        for(ll i=1;i<=n;i++){
            ll tmp = (Comb(n-1,k)*kaijo[k])%N;
            ans = (ans+(i*tmp)%N)%N;
        }
        cout<<ans<<endl;
        return 0;
    }
    for(ll i=1;i<=n;i++){
        if(i==n){
            ll tmp = (Comb(n-1,k)*kaijo[k])%N;
            tmp = (i*tmp)%N;
            ans = (ans+tmp)%N;
        }
        else{
            ll tmp1 = (Comb(n-1,k)*kaijo[k])%N;
            ll tmp2 = (((Comb(k,2)*Comb(n-2,k-2))%N)*kaijo[k-2])%N;
            ll tmp = (tmp1+tmp2)%N;
            ans = (ans+(i*tmp)%N)%N;
        }
    }
    cout<<ans<<endl;
    return 0;
}