#include <iostream>
using namespace std;

long long x, y, t = 0;
const long long M = 1000000007;
const long long N = 1000000005;

int main()
{	

	cin >> x >> y;

	if (x <= y * 2 && y <= x * 2) {
		if ((x * 2 - y) % 3 == 0 && (y * 2 - x) % 3 == 0) {
			long long a = (x * 2 - y) / 3, b = (y * 2 - x) / 3;

			t = 1;

			for (long long i = 0; i < a; i++)
				t = (t * (a + b - i)) % M;

			for (long long i = 1; i <= a; i++) {
				long long c[40];
				long long d = i;

				c[0] = i;

				for (int j = 1; (1ull << j) < N; j++) {
					c[j] = c[j - 1] * c[j - 1] % M;

					if (N & (1ull << j))
						d = (d * c[j]) % M;
				}

				t = t * d % M;
			}
		}
	}

	cout << t << endl;

	return 0;
}