#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define rep1(i, n) for (ll i = 1; i <= (n); ++i)
#define rrep(i, n) for (ll i = n; i > 0; --i)
#define bitrep(i, n) for (ll i = 0; i < (1 << n); ++i)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define yesNo(b) ((b) ? "Yes" : "No")
using ll = long long;
using ull = unsigned long long;
using ld = long double;
string alphabet = "abcdefghijklmnopqrstuvwxyz";
string ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const double pi = 3.141592653589793;
ll smallMOD = 998244353;
ll bigMOD = 1000000007;

// 2進数から10進数に変換
ll to_decimal(string s)
{
    ll res = 0;
    for (ll i = 0; i < s.size(); i++)
    {
        res = res * 2 + (s[i] - '0');
    }
    return res;
}

int main()
{
    string s, t;
    cin >> s >> t;
    stringstream ss, tt;
    ss << setw(max(s.size(), t.size())) << setfill('0') << s;
    tt << setw(max(s.size(), t.size())) << setfill('0') << t;
    s = ss.str();
    t = tt.str();
    string ans = "";
    rep(i, s.size())
    {
        ans += to_string(((s[i] - '0') + (t[i] - '0')) % 2);
    }
    cout << to_decimal(ans) << endl;
    return 0;
}