// I SELL YOU...! 
#include<iostream>
#include<vector>
#include<algorithm>
#include<functional>
#include<queue>
#include<chrono>
#include<iomanip>
#include<map>
#include<set>
using namespace std;
using ll = long long;
using P = pair<ll,ll>;
using TP = tuple<ll,ll,ll>;
void init_io(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(18);
}
signed main(){
  init_io();
  string a,b;
  cin >> a >> b;
  string s = "";
  int ans = 0;
  int n = max(a.size(), b.size());
  reverse(a.begin(), a.end());
  reverse(b.begin(), b.end());
  for (int i=0;i<n;i++) {
    int t = 0;
    if (i < a.size()) {
      t = (t + (a[i]-'0'))%2;
    }
    if (i < b.size()) {
      t = (t + (b[i]-'0'))%2;
    }
    s += to_string(t);
  }
  reverse(s.begin(), s.end());
  for (auto c: s){
    ans = ans*2 + (c-'0');
  }
  cout << ans << endl;
}