#include<iostream>
using namespace std;
long mod=1e9+7;
long power(long a,long b){return b?power(a*a%mod,b/2)*(b%2?a:1)%mod:1;}
long F[1<<17],I[1<<17];
int N,K;
long P(int a,int b){return a<b||b<0?0:F[a]*I[a-b]%mod;}
long C(int a,int b){return F[a]*I[b]%mod*I[a-b]%mod;}
main()
{
	cin>>N>>K;
	F[0]=1;
	for(int i=1;i<=N;i++)F[i]=F[i-1]*i%mod;
	I[N]=power(F[N],mod-2);
	for(int i=N;i--;)I[i]=I[i+1]*(i+1)%mod;
	long ans=0;
	for(int k=1;k<=N;k++)
	{
		(ans+=(P(N-1,K)+(k<N)*P(N-2,K-2)*C(K,2)%mod)%mod*k%mod)%=mod;
	}
	cout<<ans<<endl;
}