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

#define rep(i, n) for (int i = 0; i < (n); i++)
using ll = unsigned long long;
using Graph = vector<vector<int>>;

int main()
{
    string a, b;
    cin >> a >> b;
    if (a.size() > b.size()) // bのほうがおおきい
    {
        string tmp = a;
        a = b;
        b = tmp;
    }
    int diff = b.size() - a.size();
    for (int i = diff; i < b.size(); i++)
    {
        if (b.at(i) == a.at(i - diff))
        {
            b.at(i) = '0';
        }
        else
        {
            b.at(i) = '1';
        }
    }

    int int_b = stoi(b, 0, 2);
    cout << int_b << endl;
}