#include <bits/stdc++.h>

using namespace std;

const long long M = 1e9+7;
long long f[1111111];

long long exp(long long a, long long e) {
    if(e == 1) return a;
    if(e%2) return (a*exp(a,e-1))%M;
    return exp((a*a)%M,e/2);
}

long long inv(long long a) { return exp(a,M-2); }

int main() {
    f[0] = 1;
    for(int i=1;i<1e6;i++) f[i] = (f[i-1]*i)%M;
    int a, b;
    cin >> a >> b;
    int a3 = 2*a-b, b3 = 2*b-a;
    if(a3%3 || b3%3 || a3 < 0 || b3 < 0) cout << 0 << endl;
    else {
        long long r = (f[(a3+b3)/3]*inv(f[a3/3]))%M;
        cout <<  (r*inv(f[b3/3]))%M<< endl;
    }
    return 0;
}
