#pragma GCC optimize("O3")
#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define M 1000000007
#define M2 998244353
#define ll long long
#define pll pair<long, long>
#define REP(i, a, b) for (ll i = a; i < b; i++)
#define REPI(i, a, b) for (ll i = b - 1; i >= a; i--)
#define ff first
#define ss second
#define pb push_back
#define db pop_back
#define mp make_pair
#define mt make_tuple
#define g(a, b) get<a>(b)
#define INF (ll)1e18 + 100
#define vl vector<ll>
#define vi vector<int>
#define vll vector<pair<ll, ll>>
#define vii vector<pair<int, int>>
#define all(v) v.begin(),v.end()
#define bset(a, p) ((a) | (1ll << (p)))
#define bchk(a, p) ((a) & (1ll << (p)))
#define bxor(a, p) ((a) ^ (1ll << (p)));
#define brem(a, p) (bchk(a, p) ? (bxor(a, p)) : (a))
/*SOME BITMASK KNOWLEDGE
1)x & (x - 1):sets the last one bit of x to zero
power of two exactly when x & (x − 1) = 0.
2)x & -x:sets all the one bits to zero, except last one bit
3)x | (x - 1):inverts all the bits after the last one bit*/
#define endl "\n"
#define p0(a) cout << a << " "
#define p1(a) cout << a << endl
#define p2(a, b) cout << a << " " << b << endl
#define p3(a, b, c) cout << a << " " << b << " " << c << endl
#define p4(a, b, c, d) cout << a << " " << b << " " << c << " " << d << endl

#define o_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define o_setll tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update>
//member functions :
//1. order_of_key(k) : number of elements strictly lesser than k
//2. find_by_order(k) : k-th element in the set

ll modI(ll a, ll m);
ll gcd(ll a, ll b);
ll powM(ll x, unsigned ll y, unsigned ll m);
void pairsort(int a[], int b[], int n);
void pairsortll(ll a[],ll b[],ll n);
ll logint(ll x,ll y);
 
 
ll gcd(ll x,ll y)
{
    if(x==0) return y;
    return gcd(y%x,x);
}
 
ll powM(ll x,ll y,ll m)
{
    if(y==0) return 1;
    ll p=powM(x,y/2,m)%m;
    p=(p*p)%m;
    return (y%2==0)?p:(x*p)%m;
}
 
ll modI(ll a, ll m)
{
   return powM(a, m-2, m);
}
 
void pairsort(int a[],int b[],int n)
{
    pair<int,int> v[n];
    REP(i,0,n)
    {
        v[i].ff=a[i];
        v[i].ss=b[i];
    }
    sort(v,v+n);
    REP(i,0,n)
    {
        a[i]=v[i].ff;
        b[i]=v[i].ss;
    }
}
 
void pairsortll(ll a[],ll b[],ll n)
{
    pair<ll,ll> v[n];
    REP(i,0,n)
    {
        v[i].ff=a[i];
        v[i].ss=b[i];
    }
    sort(v,v+n);
    REP(i,0,n)
    {
        a[i]=v[i].ff;
        b[i]=v[i].ss;
    }
}
 
ll logint(ll x,ll y)
{
    ll ans=0;
    ll a=1;
    for(ll i=0;i<=x;i++)
    {
        if(x<a)
        {
            return ans;
        }
        ans++;
        a*=y;
    }
    return -1;
}

ll ncr(ll n, ll k){
    ll ans = 1;
    REP(i, 1, n+1){
        ans *= i;
        ans %= M;
    }
    ll ans1=1, ans2=1;
    REP(i,1,k+1){
        ans1*=i;
        ans1%=M;
    }
    REP(i,1,n-k+1){
        ans2*=i;
        ans2%=M;
    }
    ans *= modI(ans1,M)%M;
    ans %=M;
    ans *= modI(ans2,M)%M;
    ans %= M;
    return ans;
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    //freopen("input.txt", "r", stdin);
    //freopen("output.txt", "w", stdout);
    /*int n;
    cin>>n;
    vector<double>x(n), y(n);
    REP(i,0,n){cin>>x[i]>>y[i];}
    double ans=0;*/
    ll x,y;
    cin>>x>>y;
    if(x>y){swap(x,y);}
    ll k1, k2;
    k1 = (2*y-x);
    if(k1%3){cout<<0; return 0;}
    k1 /=3;
    k2 = x-k1;
    if(k2 < 0 || k2%2){cout<<0; return 0;}
    k2/=2;
    cout<<ncr(k1+k2,k1);

}


Measured memory_bytes: 256