#include <algorithm>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
using namespace std;
#define rep(i, n) for(int(i) = 0; (i) < (n); (i)++)
#define FOR(i, m, n) for(int(i) = (m); (i) < (n); (i)++)
#define All(v) (v).begin(), (v).end()
#define pb push_back
#define MP(a, b) make_pair((a), (b))
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
const int INF = 1 << 30;
const ll LINF = 1LL << 60;
const int MOD = 1e9 + 7;

template <uint_fast64_t MOD> class ModInt {
    using u64 = uint_fast64_t;

  public:
    u64 a;

    ModInt(const u64 x = 0) : a(x % MOD) {}
    u64 &value() { return a; }
    ModInt operator-() { return a ? MOD - a : 0; }
    ModInt operator+(const ModInt rhs) { return ModInt(*this) += rhs; }
    ModInt operator-(const ModInt rhs) { return ModInt(*this) -= rhs; }
    ModInt operator*(const ModInt rhs) { return ModInt(*this) *= rhs; }
    ModInt operator/(const ModInt rhs) { return ModInt(*this) /= rhs; }
    ModInt &operator+=(const ModInt rhs) {
        a += rhs.a;
        if(a >= MOD) {
            a -= MOD;
        }
        return *this;
    }
    ModInt &operator-=(const ModInt rhs) {
        if(a < rhs.a) {
            a += MOD;
        }
        a -= rhs.a;
        return *this;
    }
    constexpr ModInt &operator*=(const ModInt rhs) {
        a = a * rhs.a % MOD;
        return *this;
    }
    constexpr ModInt &operator/=(ModInt rhs) {
        u64 exp = MOD - 2;
        while(exp) {
            if(exp % 2) {
                *this *= rhs;
            }
            rhs *= rhs;
            exp /= 2;
        }
        return *this;
    }
    constexpr bool operator==(const ModInt rhs) { return this->a == rhs.a; }
    constexpr bool operator!=(const ModInt rhs) { return this->a != rhs.a; }
    friend constexpr ostream &operator<<(ostream &os, const ModInt<MOD> &x) {
        return os << x.a;
    }
    friend constexpr istream &operator>>(istream &is, ModInt<MOD> &x) {
        return is >> x.a;
    }
};

//二項係数（nCk mod.p;1<=k<=n<=1e7,pは素数）
template <class T> struct Combination {
    const int MOD = 1000000007;
    vector<T> fac, finv, inv;
    Combination(const int MAX) : fac(MAX), finv(MAX), inv(MAX) {
        fac[0] = fac[1] = 1;
        finv[0] = finv[1] = 1;
        inv[1] = 1;
        for(int i = 2; i < MAX; i++) {
            fac[i] = fac[i - 1] * i;
            inv[i] = -inv[MOD % i] * (MOD / i);
            finv[i] = finv[i - 1] * inv[i];
        }
    }
    T comb(int n, int k) {
        if(n < k)
            return 0;
        if(n < 0 || k < 0)
            return 0;
        return fac[n] * finv[k] * finv[n - k];
    }
};

int main() {
    using mint = ModInt<MOD>;
    mint X, Y;
    cin >> X >> Y;
    // if((mint(2) * X - Y) % mint(3) == mint(0) &&
    //    (mint(2) * Y - X) % mint(3) == mint(0))
    if((2 * X.value() - Y.value()) % 3 != 0 ||
       (2 * Y.value() - X.value()) % 3 != 0) {
        cout << 0 << endl;
    } else {
        ll a = (2 * X.value() - Y.value()) / 3;
        ll b = (2 * Y.value() - X.value()) / 3;
        Combination<mint> C(2001000);
        cout << C.comb(a + b, a) << endl;
    }
    return 0;
}

Measured memory_bytes: 47104