#define _USE_MATH_DEFINES

#include <iostream>		//cin, cout
#include <vector>		//vector
#include <algorithm>	//sort,min,max,count
#include <string>		//string,getline, to_string
#include <cstdlib>		//abs(int)
#include <utility>		//swap, pair
#include <deque>		//deque
#include <climits>		//INT_MAX
#include <bitset>		//bitset
#include <cmath>		//sqrt, ceil. M_PI, pow, sin
#include <ios>			//fixed
#include <iomanip>		//setprecision
#include <sstream>		//stringstream
#include <numeric>		//gcd, assumlate
#include <random>		//randam_device
#include <limits>		//numeric_limits

using namespace std;
constexpr long long int D_MOD = 1000000007;

inline unsigned int BinToUInt(const string S) {
    //2進数(文字列)を10進数(unsigned int)に変換する

    unsigned int result = 0;
    for (unsigned int i = 0; i < S.length(); i++) {
        switch (S[i]) {
        case '0':result *= 2; break;
        case '1':result = result * 2 + 1; break;
        }
    }
    return result;
}

int main() {

    string A, B;
    cin >> A >> B;

    int ans;

    if (A.size() > B.size()) {
        for (int i = 1; i <= B.size(); i++) {
            if (A.at(A.size() - i) == B.at(B.size() - i)) {
                A.at(A.size() - i) = '0';
            }
            else {
                A.at(A.size() - i) = '1';
            }
        }
        ans = BinToUInt(A);
    }
    else {
        for (int i = 1; i <= A.size(); i++) {
            if (A.at(A.size() - i) == B.at(B.size() - i)) {
                B.at(B.size() - i) = '0';
            }
            else {
                B.at(B.size() - i) = '1';
            }
        }
        ans = BinToUInt(B);
    }

    cout << ans << endl;
    
    return 0;

}