#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
#define Inf 1000000001

struct combi{
	deque<mint> kaijou;
	deque<mint> kaijou_;
	
	combi(int n){
		kaijou.push_back(1);
		for(int i=1;i<=n;i++){
			kaijou.push_back(kaijou[i-1]*i);
		}
		
		mint b=kaijou[n].inv();
		
		kaijou_.push_front(b);
		for(int i=1;i<=n;i++){
			int k=n+1-i;
			kaijou_.push_front(kaijou_[0]*k);
		}
	}
	
	mint combination(int n,int r){
		if(r>n)return 0;
		mint a = kaijou[n]*kaijou_[r];
		a *= kaijou_[n-r];
		return a;
	}
	
	mint junretsu(int a,int b){
		mint x = kaijou_[a]*kaijou_[b];
		x *= kaijou[a+b];
		return x;
	}
	
	mint catalan(int n){
		return combination(2*n,n)/(n+1);
	}
	
};

int main(){
	
	combi C(1000000);
	
	int N,K;
	cin>>N>>K;
	K--;
	mint ans = 0;
	mint cur = C.kaijou_[N];
	deque<mint> D;
	rep(i,N){
		cur *= N+K - i;
		D.push_back(N+K-i);
	}
	rep(i,N){
	//	cout<<cur.val()<<','<<D.back().val()<<endl;
		mint t = C.combination(N-1,i);
		if(D.front().val() > D.back().val() && D.back()!=0)ans += t*cur;
		if(D.front()!=0){
			cur /= D.front();
		}
		D.push_back(D.back()-1);
		if(D.back()!=0)cur *= D.back();
		D.pop_front();		
	}
	cout<<ans.val()<<endl;
	
	return 0;
}