#include <iostream>
#include <iomanip>
#include <math.h>
#include <string>
#include <algorithm>
#include <vector>
#include <numeric>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <bitset>
using namespace std;

#define ll long long int
#define rep(i, a, n) for (ll i = a; i < n; i++)
#define repm(i, a, n) for (ll i = a; i >= n; i--)
#define INF 1e9
#define LINF 1e17
#define MOD (int)(1e9 + 7)
#define mod (int)(1e9 + 7)
#define pi 3.141592653589
#define pii pair<int, int>
#define pll pair<ll, ll>
#define vi vector<int>
#define vd vector<double>
#define vb vector<bool>
#define vs vector<string>
#define vii vector<vector<int>>
#define vll vector<ll>
#define vllll vector<vector<ll>>
#define ALL(a) (a).begin(), (a).end()
#define sort_v(a) sort(a.begin(), a.end())
#define reverse_v(a) reverse(a.begin(), a.end())

void print(bool c)
{
    (c) ? (cout << "Yes" << endl) : (cout << "No" << endl);
}

void Print(bool c)
{
    (c) ? (cout << "YES" << endl) : (cout << "NO" << endl);
}

//最小公倍数
template <typename T>
T gcd(T a, T b)
{
    while (1)
    {
        if (a < b)
            swap(a, b);
        if (b == 0)
            break;
        a %= b;
    }
    return a;
}

//最大公約数
template <typename T>
T lcm(T a, T b)
{
    return a * b / gcd(a, b);
}
//セカンドキー->ファーストキーの順ソート
bool cmp(const pii &a, const pii &b)
{
    if (a.second != b.second)
        return a.second < b.second;
    return a.first < b.first;
}

//右下左上
int dx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
int dy[8] = {0, 1, 0, -1, 1, -1, 1, -1};

int eve(int x)
{
    if (x % 400 == 0)
        return 1;
    if (x % 100 == 0)
        return 0;
    if (x % 4 == 0)
        return 1;
    return 0;
}

struct mint
{
    ll x; // typedef long long ll;
    mint(ll x = 0) : x((x % mod + mod) % mod) {}
    mint operator-() const { return mint(-x); }
    mint &operator+=(const mint a)
    {
        if ((x += a.x) >= mod)
            x -= mod;
        return *this;
    }
    mint &operator-=(const mint a)
    {
        if ((x += mod - a.x) >= mod)
            x -= mod;
        return *this;
    }
    mint &operator*=(const mint a)
    {
        (x *= a.x) %= mod;
        return *this;
    }
    mint operator+(const mint a) const { return mint(*this) += a; }
    mint operator-(const mint a) const { return mint(*this) -= a; }
    mint operator*(const mint a) const { return mint(*this) *= a; }
    mint pow(ll t) const
    {
        if (!t)
            return 1;
        mint a = pow(t >> 1);
        a *= a;
        if (t & 1)
            a *= *this;
        return a;
    }

    // for prime mod
    mint inv() const { return pow(mod - 2); }
    mint &operator/=(const mint a) { return *this *= a.inv(); }
    mint operator/(const mint a) const { return mint(*this) /= a; }
};
istream &operator>>(istream &is, const mint &a) { return is >> a.x; }
ostream &operator<<(ostream &os, const mint &a) { return os << a.x; }

struct combination
{
    vector<mint> fact, ifact;
    combination(int n) : fact(n + 1), ifact(n + 1)
    {
        //assert(n < mod);
        fact[0] = 1;
        for (int i = 1; i <= n; ++i)
            fact[i] = fact[i - 1] * i;
        ifact[n] = fact[n].inv();
        for (int i = n; i >= 1; --i)
            ifact[i - 1] = ifact[i] * i;
    }
    mint operator()(int n, int k)
    {
        if (k < 0 || k > n)
            return 0;
        return fact[n] * ifact[k] * ifact[n - k];
    }
};

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

    if ((x + y) % 3 != 0)
        return cout << 0 << endl, 0;
    combination c(2000000);
    ll cnt = (x + y) / 3;
    mint a, b;
    a = c(cnt, x - cnt);
    //cout << cnt << " " << a << endl;
    cout << a << endl;
}


Measured memory_bytes: 31488