include

define int long long

using namespace std; const int mod = 1e9 + 7; int yang[2001][2001];

signed main() {

int n, m, ans = 0;
cin >> n >> m;
yang[0][0] = 1;

for (int i = 1; i <= 2000; i++) {

	yang[i][0] = 1;

	for (int j = 1; j <= i; j++) {

		yang[i][j] = yang[i - 1][j - 1] + yang[i - 1][j];
		yang[i][j]%=mod;
	}
}

for (int i = 1; i <= n; i++) {

	for (int j = i; j <= n; j++) {

		int k = yang[m + n - j - 1][n - j] * yang[m + i - 2][i - 1];
		k = (k + mod) % mod;
		ans += k;
		ans = (ans + mod) % mod;
	}
}

cout << ans;
return 0;

}