#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
//https://atcoder.jp/contests/abc145/tasks/abc145_d
long int modo = 1000000007;

long int binNewt(long int N,long int n1){
    if(n1 == 0)
        return 1;
    long int i, j, iMin = N - n1, jMin = 0, *C;
    C = malloc((n1 + 1) * sizeof(long int));
    C[0] = 1;
    for (i = 1; i <= n1; i++){
        C[i] = 1;
        for (j = i - 1; j > 0; j--){
            C[j] = C[j - 1] + C[j];
            if(C[j] > modo)
                C[j] -= modo;
        }
    }
    for (i = n1 + 1; i <= iMin; i++)
        for (j = n1; j > 0; j--){
            C[j] = (C[j - 1] + C[j]);
            if(C[j] > modo)
                C[j] -= modo;
        }
    for (i = iMin + 1; i < N; i++){
        for (j = n1; j > jMin; j--){
            C[j] = (C[j - 1] + C[j]);
            if(C[j] > modo)
                C[j] -= modo;
        }
        jMin++;
    }
    return (C[n1] + C[n1 - 1]) % modo;
}

int main() {
    long int x, y, n1, N;
    scanf("%ld %ld\n", &x, &y);
    n1 =  (x < y) ? (2 * x - y) / 3 : (2 * y - x) / 3;
    N = y + x;
    if((N % 3 != 0) || n1 < 0 || n1 > N)
        printf("0\n");
    else{
        N /= 3;
        printf("%ld\n", binNewt(N, n1));
    }
    return 0;
}