#include <bits/stdc++.h>

using namespace std;
using ll = long long int;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vb = vector<bool>;
using vs = vector<string>;
using vvi = vector<vector<int>>;
using vvl = vector<vector<ll>>;
using vvb = vector<vector<bool>>;
using vvs = vector<vector<string>>;
template <typename T>
using vv = vector<vector<T>>;
template <typename T>
using vvv = vector<vector<vector<T>>>;
template <typename T>
using pq = priority_queue<T>;
template <typename T>
using pqg = priority_queue<T, vector<T>, greater<T>>;

const int INF = 1e9;
const ll LINF = 1e18;
const ll MOD = 1e9 + 7;
const int DX[4] = {1, 0, -1, 0};
const int DY[4] = {0, 1, 0, -1};

#define _sel(_1, _2, x, ...) x
#define repn(i, n) for (ll i = 0; i < (n); i++)
#define reps(i, a, b) for (ll i = (a); i < (b); i++)
#define rep(i, ...) _sel(__VA_ARGS__, reps, repn)(i, __VA_ARGS__)
#define reppn(i, n) for (ll i = 1; i <= (n); i++)
#define repps(i, a, b) for (ll i = (a); i <= (b); i++)
#define repp(i, ...) _sel(__VA_ARGS__, repps, reppn)(i, __VA_ARGS__)
#define rrepn(i, n) for (ll i = (n)-1; i >= 0; i--)
#define rreps(i, a, b) for (ll i = (b)-1; i >= (a); i--)
#define rrep(i, ...) _sel(__VA_ARGS__, rreps, rrepn)(i, __VA_ARGS__)
#define rreppn(i, n) for (ll i = (n); i >= 1; i--)
#define rrepps(i, a, b) for (ll i = (b); i >= (a); i--)
#define rrepp(i, ...) _sel(__VA_ARGS__, rrepps, rreppn)(i, __VA_ARGS__)

#define pb push_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
#define rng(v) (v).begin(), (v).end()
#define rrng(v) (v).rbegin(), (v).rend()
#define siz(x) int((x).size())
#define pow2(x) (1ll << (x))
#define bit(x, n) ((x) >> (n)&1)
#define prt(x) cout << (x) << endl
#define dbg(x) dbgn(#x, x)

template <typename T, typename U> inline bool umax(T &m, U x) { if (m < x) { m = x; return true; } return false; }
template <typename T, typename U> inline bool umin(T &m, U x) { if (m > x) { m = x; return true; } return false; }
template <typename T> inline void errv(T &v) { for (auto x : v) cerr << x << " "; cerr << endl; }
inline void errv(vb &v) { for (auto x : v) cerr << (x ? 1 : 0) << " "; cerr << endl; }
template <typename T> inline void dbgn(string n, T x) { cerr << n << ": " << x << endl; }
template <typename T> inline void dbgn(string n, vector<T> &v) { cerr << n << ": "; errv(v); }
template <typename T> inline void dbgn(string n, vv<T> &m) { cerr << n << ":" << endl; for (auto &v : m) errv(v); }

template <std::uint_fast64_t Modulus>
class modint {
    using u64 = std::uint_fast64_t;

public:
    u64 a;

    constexpr modint(const u64 x = 0) noexcept : a(x % Modulus) {}
    constexpr u64 &value() noexcept { return a; }
    constexpr const u64 &value() const noexcept { return a; }
    constexpr modint operator+(const modint rhs) const noexcept {
        return modint(*this) += rhs;
    }
    constexpr modint operator-(const modint rhs) const noexcept {
        return modint(*this) -= rhs;
    }
    constexpr modint operator*(const modint rhs) const noexcept {
        return modint(*this) *= rhs;
    }
    constexpr modint operator/(const modint rhs) const noexcept {
        return modint(*this) /= rhs;
    }
    constexpr modint &operator+=(const modint rhs) noexcept {
        a += rhs.a;
        if (a >= Modulus) {
            a -= Modulus;
        }
        return *this;
    }
    constexpr modint &operator-=(const modint rhs) noexcept {
        if (a < rhs.a) {
            a += Modulus;
        }
        a -= rhs.a;
        return *this;
    }
    constexpr modint &operator*=(const modint rhs) noexcept {
        a = a * rhs.a % Modulus;
        return *this;
    }
    constexpr modint &operator/=(modint rhs) noexcept {
        u64 exp = Modulus - 2;
        while (exp) {
            if (exp % 2) {
                *this *= rhs;
            }
            rhs *= rhs;
            exp /= 2;
        }
        return *this;
    }
};

int main()
{
    int x, y;
    cin >> x >> y;

    if ((x + y) % 3 != 0)
    {
        prt(0);
        return 0;
    }

    int n = (x + y) / 3;

    if (abs(x - y) > n)
    {
        prt(0);
        return 0;
    }

    int a = x - n;
    int b = y - n;

    modint<MOD> ans = 1;
    repp(i, n)
        ans *= i;
    repp(i, a)
        ans /= i;
    repp(i, b)
        ans /= i;
    prt(ans.a);

    return 0;
}


Measured memory_bytes: 256