#include <bits/stdc++.h>
using namespace std;
using lint = long long;
int main() {
  string s, t;
  cin >> s >> t;
  reverse(s.begin(), s.end());
  reverse(t.begin(), t.end());
  string ans = "";
  for (int i = 0; i < min(s.size(), t.size()); i++) {
  	if (s[i] == '1' &&t[i] == '1') ans += '0';
    else if (s[i] == '1' ||t[i] == '1') ans+='1';
    else ans+='0';
  }
  for (int i = min(s.size(), t.size()); i < max(s.size(), t.size()); i++) {
    if (s.size() < t.size()) ans += t[i];
    else ans += s[i];
  }
  int num = 0;
  for (int i = 0;i < 30; i++) {
  	if (ans[i] == '1') num += (1<<i);
  }
  cout << num << endl;
  
}