#include <iostream>
#include <iomanip>
#include <vector>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <algorithm>
#include <cmath>
#include <iterator>


using namespace std;

using i64 = int64_t;
// using u64 = uint64_t;

template<class T>
using VV = vector<vector<T>>;

#define REP(i, n) for(i64 i = 0; i < i64(n); i++)
#define REP1(i, n) for(i64 i = 1; i <= i64(n); i++)

i64 INF = 100100100100100L;

i64 direct[8][2] = {
  {1, 0}, {0, -1}, {-1, 0}, {0, 1},
  {1, -1}, {-1, -1}, {-1, 1}, {1, 1}
};


template<class T, class S>
ostream &operator<<(ostream &os, pair<T, S> p);


template<class T>
ostream &operator<<(ostream &os, const vector<T> &v)
{
  for(i64 i = 0; i < i64(v.size()); i++) {
    if (i > 0) os << ' ';
    os << v[i];
  }

  return os;
}

template<class T>
ostream &operator<<(ostream &os, const set<T> &st)
{
  bool first = true;
  for(const T &it: st)
  if (first) {
      first = false;
      os << it;
  } else{
    os << ' ' << it;
  }

  return os;
}

template<class T, class S>
ostream &operator<<(ostream &os, map<T, S> &mp)
{
  bool first = true;
  for(const auto &[f, l]: mp)
  if (first) {
      first = false;
      os << '{' << f << "-> " << l << '}';
  } else{
    os << ", {" << f << "-> " << l << '}';
  }

  return os;
}


template<class T, class S>
ostream &operator<<(ostream &os, pair<T, S> p)
{
  os << '{' << p.first << ", " << p.second << '}';

  return os;
}



int main()
{
  i64 A, B;
  cin >> A >> B;

  cout << (A ^ B) << endl;

  return 0;
}