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

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<ll, ll> pll;
typedef pair<ull, ull> pullull;
typedef pair<ll, int> plli;
typedef pair<int, pii> pipii;
typedef vector<vector<int> > mati;
typedef vector<vector<double> > matd;
typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;
typedef vector<vector<vector<ll>>> vvvll;
typedef vector<bool> vb;
typedef vector<vector<bool>> vvb;
typedef vector<vector<vector<bool>>> vvvb;
typedef vector<pll> vpll;
typedef vector<vpll> vvpll;

#define FOR(i,x,y) for(ll i=(ll)x; i<(ll)y; ++i)
#define REP(i,y) FOR(i, 0, y)
#define RFOR(i,x,y) for(ll i=(ll)x; i>=(ll)y; --i)
#define RREP(i,x) RFOR(i, x, 0)
#define ALL(a) a.begin(), a.end()
#define pb push_back
#define debug_printf(x...) cerr << "line " << __LINE__ << " : "; debug_printf_in(x);

template <typename First>
void debug_printf_in(First first){
  cerr << first << endl;
  return;
}

template <typename First, typename... Rest>
void debug_printf_in(First first, Rest... rest){
  cerr << first << " ";
  debug_printf_in(rest...);
  return;
}

void IN(void){
  return;
}

template <typename First, typename... Rest>
void IN(First& first, Rest&... rest){
  cin >> first;
  IN(rest...);
  return;
}

template <typename First>
void OUT(First first){
  cout << first << endl;
  return;
}

template <typename First, typename... Rest>
void OUT(First first, Rest... rest){
  cout << first << " ";
  OUT(rest...);
  return;
}

template<class t, class u> void chmax(t&a,u b){if(a<b)a=b;};
template<class t, class u> void chmin(t&a,u b){if(a>b)a=b;};
int popcount(int t){return __builtin_popcount(t);} //GCC
int popcount(ll t){return __builtin_popcountll(t);} //GCC

template <typename T>
void vec_print(vector<T> VEC){
  REP(i, VEC.size()){
    cout << VEC[i] << " ";
  }
  cout << "\n";
};

template <typename T>
void mat_print(vector<vector<T> > MAT){
  REP(i, MAT.size()){
    REP(j, MAT[i].size()){
      cout << MAT[i][j] << " ";
    }
    cout << "\n";
  }
};

template <typename CLASS1, typename CLASS2>
class HOGE{
  public:
    CLASS1 key;
    CLASS2 value;
    HOGE(void){
      return;
    };
    HOGE(CLASS1 key, CLASS2 value){
      this->key = key;
      this->value = value;
    };
    ~HOGE(void){
      return;
    };

    void print(void){
      cout << "key : " << key << ", value : " << value << "\n";
      return;
    };
    
    bool operator==(const HOGE &obj){
      return (this->value == obj.value);
    };
    bool operator<(const HOGE &obj){
      return (this->value < obj.value);
    };
    bool operator>(const HOGE &obj){
      return (this->value > obj.value);
    };
};

template <typename CLASS1, typename CLASS2>
bool operator==(const HOGE<CLASS1, CLASS2> &hoge1, const HOGE<CLASS1, CLASS2> &hoge2){
  return hoge1.value == hoge2.value;
};

template <typename CLASS1, typename CLASS2>
bool operator<(const HOGE<CLASS1, CLASS2> &hoge1, const HOGE<CLASS1, CLASS2> &hoge2){
  return hoge1.value < hoge2.value;
};

template <typename CLASS1, typename CLASS2>
bool operator>(const HOGE<CLASS1, CLASS2> &hoge1, const HOGE<CLASS1, CLASS2> &hoge2){
  return hoge1.value > hoge2.value;
};

constexpr int INF = (1<<30);
constexpr ll INFLL = 1LL<<62;
constexpr long double EPS = 1e-12;
constexpr ll MOD = (ll)((1E+9)+7);

class Modulo{
  private:
    ll MAX = MOD;
    vll fac_v, finv_v, inv_v;
  public:

    void Modulo_setting(ll MAX_){
      MAX = MAX_;

      fac_v.resize(MAX);
      finv_v.resize(MAX);
      inv_v.resize(MAX);

      fac_v[0] = fac_v[1] = 1;
      finv_v[0] = finv_v[1] = 1;
      inv_v[1] = 1;
      for(int i=2; i<=MAX; ++i){
        //i!
        fac_v[i] = (fac_v[i-1]*i)%MOD;
        //i^{-1}
        inv_v[i] = (MOD-(inv_v[MOD%i]*(MOD/i))%MOD)%MOD;
        //(i!)^{-1}
        finv_v[i] = (finv_v[i-1]*inv_v[i])%MOD;
      }
    };

    Modulo(ll MAX_){
      Modulo_setting(MAX_);
      return;
    };

    Modulo(void){
      Modulo_setting(MOD);
      return;
    };

    ~Modulo(void){
      return;
    };

    ll inv(ll n){
      if(n<0 || n>MAX){
        fprintf(stderr, "n range error\n");
        exit(0);
      }
      return inv_v[n];
    };

    ll fac(ll n){
      if(n<0 || n>MAX){
        fprintf(stderr, "n range error\n");
        exit(0);
      }
      return fac_v[n];
    };

    ll inv_fac(ll n){
      if(n<0 || n>MAX){
        fprintf(stderr, "n range error\n");
        exit(0);
      }
      return finv_v[n];
    };

    ll ModCom(ll n, ll k){
      if(n<k) return 0;
      if(n<0 || k<0) return 0;
      return (fac_v[n]*((finv_v[k]*finv_v[n-k])%MOD))%MOD;
    };

    ll ExCom(ll n, ll k){
      if(n<k) return 0;
      if(n<0 || k<0) return 0;
      ll ans = 1;
      k = min(k, n-k);
      for(ll i=0; i<k; ++i){
        ans *= (n-i);
        ans /= (i+1);
      }
      return ans;
    };

    ll pow(ll x, ll n){
      ll res=1;
      while(n>0){
        if(n&1) res=res*x%MOD;
        x=x*x%MOD;
        n>>=1;
      }
      return res;
    };

    unordered_map<ll, ll> prime_decomposer(ll n){
      unordered_map<ll, ll> mp;
      for(ll i=2; i*i<=n; ++i){
        while(n%i==0){
          mp[i]++;
          n/=i;
        }
      }
      if(n!=1) mp[n]++;
      return mp;
    };

    ll LCM(vector<ll> vec){
      unordered_map<ll, ll> mp;
      for(ll i=0; i<vec.size(); ++i){
        unordered_map<ll, ll> mp_tmp = prime_decomposer(vec[i]);
        for(auto e : mp_tmp){
          mp[e.first] = max(mp[e.first], e.second);
        }
      }
      ll lcm=1;
      for(auto e : mp){
        lcm = (lcm*pow(e.first, e.second))%MOD;
      }
      return lcm;
    };

    ll GCM(vector<ll> vec){
      unordered_map<ll, ll> mp;
      for(ll i=0; i<vec.size(); ++i){
        unordered_map<ll, ll> mp_tmp = prime_decomposer(vec[i]);
        for(auto e : mp_tmp){
          if(mp.find(e.first)==mp.end()) mp[e.first] = e.second;
          else mp[e.first] = min(mp[e.first], e.second);
        }
      }
      ll gcm=1;
      for(auto e : mp){
        gcm = (gcm*pow(e.first, e.second))%MOD;
      }
      return gcm;
    };
};



int main(){
  cin.tie(0); // cut the cin and cout (default, std::flush is performed after std::cin)
  ios::sync_with_stdio(false); // cut the iostream and stdio (DON'T endl; BUT "\n";)

  ll X, Y;
  IN(X,Y);

  if((X+Y)%3!=0){
    OUT(0);
    return 0;
  }

  ll N = (X+Y)/3;
  X -= N;
  Y -= N;
  if(X<0 || Y<0){
    OUT(0);
    return 0;
  }

  Modulo que(1E6+1);

  debug_printf(X+Y, X);

  OUT(que.ModCom(X+Y, X));

  return 0;
}


Measured memory_bytes: 23680