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

void fast_io() {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
}

int main() {
	fast_io();
	string a, b;
	cin >> a >> b;
	int a_num = 0, b_num = 0;
	for (int i = 0; i < a.size(); i++) {
		a_num = 2 * a_num + (a[i] - '0');
	}
	for (int i = 0; i < b.size(); i++) {
		b_num = 2 * b_num + (b[i] - '0');
	}
	cout << (a_num ^ b_num) << endl;
}