//#pragma GCC target("avx2")
//#pragma GCC optimize("O3")
//#pragma GCC optimize("unroll-loops")
#include <iostream>
#include <iomanip>
#include <algorithm>
#include <vector>
#include <string>
#include <set>
#include <map>
#include <cassert>
#include <cmath>
#include <tuple>
#include <queue>
#include <bitset>
#include <complex>
#define _USE_MATH_DEFINES
#include <math.h>
using namespace std;
using lg = long long;
using pii = pair<int, int>;
using pll = pair<lg, lg>;
#define TEST clog << "TEST" << endl
#define IINF 2147483647
#define LLINF 9223372036854775807LL
//#define AMARI 998244353
#define AMARI 1000000007
#define TEMOTO ((sizeof(long double) == 16) ? false : true)
#define TIME_LIMIT 1980 * (TEMOTO ? 1 : 1000)
#define el '\n'
#define El '\n'

#define MULTI_TEST_CASE false
void solve(void) {
    string s,t;
    cin >> s >> t;
    lg ans = 0;
    if (s.size() < t.size())swap(s, t);
    string nt;
    for (int i = 0; i < (int)s.size() - (int)t.size(); i++)nt.push_back('0');
    for (int i = 0; i < t.size(); i++)nt.push_back(t[i]);
    int cnt = 0;
    for (int i = s.size() - 1; i >= 0; i--) {
        if (s[i] != nt[i])ans += (1LL << cnt);
        cnt++;
    }
    cout << ans << el;
    return;
}

void calc(void) {
    return;
}

int main(void) {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int t = 1;
    if (MULTI_TEST_CASE)cin >> t;
    while (t--) {
        //calc();
        solve();
    }
    return 0;
}