#include <algorithm>
#include <cassert>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <ctime>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iostream>
#include <iterator>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>

using namespace std;
using ll = long long;

#define REP(i, a) for (int i = 0; i < (a); ++i)
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define FORR(i, a, b) for (int i = (a)-1; i >= (b); --i)
#define ALL(obj) (obj).begin(), (obj).end()
#define YESNO(cond, yes, no) \
    { cout << ((cond) ? (yes) : (no)) << endl; }
#define SORT(list) sort(ALL((list)));
#define RSORT(list) sort((list).rbegin(), (list).rend())
#define ASSERT(cond, mes) assert(cond&& mes)

constexpr int MOD = 1'000'000'007;
constexpr int INF = 1'050'000'000;

template <typename T>
T round_up(const T& a, const T& b) {
    return (a + (b - 1)) / b;
}

template <typename T1, typename T2>
istream& operator>>(istream& is, pair<T1, T2>& p) {
    is >> p.first >> p.second;
    return is;
}

template <typename T1, typename T2>
ostream& operator<<(ostream& os, pair<T1, T2>& p) {
    os << p.first << p.second;
    return os;
}

template <typename T>
istream& operator>>(istream& is, vector<T>& v) {
    REP(i, (int)v.size())
    is >> v[i];
    return is;
}

template <typename T>
T clamp(T& n, T a, T b) {
    if (n < a) n = a;
    if (n > b) n = b;
    return n;
}

template <typename T>
static T GCD(T u, T v) {
    T r;
    while (v != 0) {
        r = u % v;
        u = v;
        v = r;
    }
    return u;
}

template <typename T>
static T LCM(T u, T v) {
    return u / GCD(u, v) * v;
}

template <class T>
std::vector<T> enum_div(T n) {
    std::vector<T> ret;
    for (T i = 1; i * i <= n; i++) {
        if (n % i == 0) {
            ret.push_back(i);
            if (i * i != n) { ret.push_back(n / i); }
        }
    }
    return ret;
}

bool isPrime(ll num) {
    if (num < 2)
        return false;
    else if (num == 2)
        return true;
    else if (num % 2 == 0)
        return false;

    for (ll i = 3; i * i <= num; i += 2) {
        if (num % i == 0) { return false; }
    }

    return true;
};

template <typename T>
bool chmin(T& a, const T& b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

template <typename T>
bool chmax(T& a, const T& b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

template <class T>
bool is_integer(T x) {
    return std::floor(x) == x;
}

struct ToUpper {
    char operator()(char c) {
        return toupper(c);
    }
};

struct ToLower {
    char operator()(char c) {
        return tolower(c);
    }
};

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(20);

    int X, Y;
    cin >> X >> Y;

    auto comb = [](int n, int r) {
        if (n - r < r) r = n - r;
        if (r == 0) return 1LL;
        if (r == 1) return (ll)n;
        vector<int> num(r);
        vector<int> den(r);

        REP(k, r) {
            num[k] = n - r + k + 1;
            den[k] = k + 1;
        }

        FOR(p, 2, r + 1) {
            int piv = den[p - 1];
            if (piv > 1) {
                int off = (n - r) % p;
                for (int k = p - 1; k < r; k += p) {
                    num[k - off] /= piv;
                    den[k] /= piv;
                }
            }
        }

        ll res = 1;
        REP(k, r) {
            if (num[k] > 1) {
                res *= num[k];
                res %= MOD;
            }
        }

        return res;
    };

    auto solve = [comb](int X, int Y) {
        if ((X + Y) % 3 != 0) return 0LL;
        int m = -((Y - 2 * X) / 3);
        if (m < 0) return 0LL;
        int n = X - 2 * m;
        if (n < 0) return 0LL;
        return comb(n + m, n);
    };

    cout << solve(X, Y) << endl;
}


Measured memory_bytes: 2816