#include <bits/stdc++.h>
using namespace std;

#define int int64_t

int p(int a , int b , int m){
	int x = 1;
	for(int i = 0; i < 30; i++){
		if((1<<i)&b){
			x*=a;
			x%=m;
		}
		a*=a;
		a%=m;
	}
	return x;
}

int M = 1e9+7;

vector<int> f;

int32_t main() {
	int b , c;cin >> b >> c;
	f.push_back(1);
	for(int i = 1; i <= 2*c; i++){
		f.push_back((f.back()*i)%M);
	}
	int d = (f[c-1+c-b]*p(f[c-1]*f[c-b] , M-2 , M))%M;
	int e = (f[c-1+c-b]*p(f[c]*f[c-b-1] , M-2 , M))%M;
	cout << (d-e)%M << endl;
}