#include<cstdio>
using namespace std;
const int maxn=2000+2;
const int mod=1e9+7;
int a,b;
int C[maxn][maxn];
void init(){
	C[0][0]=1;
	for (int i=1;i<maxn;i++){
		C[i][0]=C[i][i]=1;
		for (int j=1;j<i;j++) C[i][j]=(C[i-1][j]+C[i-1][j-1])%mod;
	}
}
int main(){
	init();
	scanf("%d%d",&a,&b);
	int ans=a+1;
	for (int i=1;i<b;i++){
		if (b-i>a) continue;
		for (int j=1;j<=b-i;j++){
			if ((b-i)+(b-i-j)>a) continue;
			ans=(ans+1LL*C[b-1][i-1]*C[b-i-1][j-1]%mod*C[a-(b-i-1)-(b-i-j-1)][2]%mod)%mod;
		}
	}
	printf("%d",ans);
	return 0;
}