#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
#define rep(i,a,b) for(int i = a; i < b; ++i)
#define rrep(i,a,b) for(int i = a; i >= b; --i)
#define all(x) (x).begin(),(x).end()

int main(){
  bitset<30> a, b;
  cin >> a >> b;
  bitset<30> ans;
  ans = a ^ b;

  cout << ans.to_ullong() << endl;




  return 0;
}