#include <bits/stdc++.h>
#include <atcoder/all>
using ll = long long;
#define MOD 1000000007
#define Mod 998244353
const int MAX = 1000000005;
const long long INF = 1000000000000000005LL;
using namespace std;
using namespace atcoder;



int main() {
    ios::sync_with_stdio(0);cin.tie();
    string A, B;
    cin >> A >> B;
    reverse(A.begin(), A.end());
    reverse(B.begin(), B.end());
    vector<int> bit(30);
    for (int i = 0; i < 30; i++) {
        int a = (A.size() > i ? A[i] - '0' : 0), b = (B.size() > i ? B[i] - '0' : 0);
        bit[i] = a^b;
    }
    int ans = 0;
    for (int i = 0; i < 30; i++) {
        ans += bit[i] * (1 << i);
    }
    cout << ans << endl;
}