#include <bits/stdc++.h>
using namespace std;

using ll = long long;

const int mod = 1e9 + 7;

template <int mod> struct ModInt {
    int x;

    ModInt() : x(0) {}

    ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}

    ModInt &operator+=(const ModInt &p) {
        if ((x += p.x) >= mod)
            x -= mod;
        return *this;
    }

    ModInt &operator-=(const ModInt &p) {
        if ((x += mod - p.x) >= mod)
            x -= mod;
        return *this;
    }

    ModInt &operator*=(const ModInt &p) {
        x = (int)(1LL * x * p.x % mod);
        return *this;
    }

    ModInt &operator/=(const ModInt &p) {
        *this *= p.inverse();
        return *this;
    }

    ModInt operator-() const { return ModInt(-x); }

    ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }

    ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }

    ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }

    ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }

    bool operator==(const ModInt &p) const { return x == p.x; }

    bool operator!=(const ModInt &p) const { return x != p.x; }

    ModInt inverse() const {
        int a = x, b = mod, u = 1, v = 0, t;
        while (b > 0) {
            t = a / b;
            swap(a -= t * b, b);
            swap(u -= t * v, v);
        }
        return ModInt(u);
    }

    ModInt pow(int64_t n) const {
        ModInt ret(1), mul(x);
        while (n > 0) {
            if (n & 1)
                ret *= mul;
            mul *= mul;
            n >>= 1;
        }
        return ret;
    }

    friend ostream &operator<<(ostream &os, const ModInt &p) {
        return os << p.x;
    }

    friend istream &operator>>(istream &is, ModInt &a) {
        int64_t t;
        is >> t;
        a = ModInt<mod>(t);
        return is;
    }

    static int get_mod() { return mod; }
};

// TにはModIntを渡す
template <typename T> struct Combination {
    vector<T> _fact, _rfact, _inv;

    Combination(int sz) : _fact(sz + 1), _rfact(sz + 1), _inv(sz + 1) {
        _fact[0] = _rfact[sz] = _inv[0] = 1;
        for (int i = 1; i <= sz; i++)
            _fact[i] = _fact[i - 1] * i;
        _rfact[sz] /= _fact[sz];
        for (int i = sz - 1; i >= 0; i--)
            _rfact[i] = _rfact[i + 1] * (i + 1);
        for (int i = 1; i <= sz; i++)
            _inv[i] = _rfact[i] * _fact[i - 1];
    }
    inline T fact(int k) const { return _fact[k]; }

    inline T rfact(int k) const { return _rfact[k]; }

    inline T inv(int k) const { return _inv[k]; }

    T P(int n, int r) const {
        if (r < 0 || n < r)
            return 0;
        return fact(n) * rfact(n - r);
    }

    T C(int p, int q) const {
        if (q < 0 || p < q)
            return 0;
        return fact(p) * rfact(q) * rfact(p - q);
    }

    T H(int n, int r) const {
        if (n < 0 || r < 0)
            return 0;
        return r == 0 ? 1 : C(n + r - 1, n);
    }
};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int X, Y;
    cin >> X >> Y;
    if ((X + Y) % 3) {
        cout << 0 << endl;
        return 0;
    }
    int k = (X + Y) / 3;
    if (X < k || Y < k) {
        cout << 0 << endl;
        return 0;
    }
    Combination<ModInt<mod>> comb(k);
    cout << comb.C(k, X - k) << endl;
}

Measured memory_bytes: 8192