#include <bits/stdc++.h>
// #include <atcoder/dsu>
// #include <atcoder/modint>
using namespace std;
// using namespace atcoder;
#define SZ(x) (int)(x).size()
#define dout(x) printf("%.10f\n", (double)(x))
#define ALL(s) (s).begin(), (s).end()
#define so(V) sort(ALL(V))
#define rev(V) reverse(ALL(V))
typedef pair<int, int> P;
typedef pair<long, long> Pl;
typedef vector<vector<int>> vvi;
typedef vector<vector<long>> vvl;

int main()
{
    string A, B;
    cin >> A >> B;
    rev(A);
    rev(B);
    long kotae = 0, a = 1;
    for (int i = 0; i < max(SZ(A), SZ(B)); i++)
    {
        if (i < SZ(A) && i < SZ(B))
        {
            if (A[i] != B[i])
            {
                kotae += a;
            }
        }
        else
        {
            if (i < SZ(A))
            {
                if (A[i] == '1')
                {
                    kotae += a;
                }
            }
            else
            {
                if (B[i] == '1')
                {
                    kotae += a;
                }
            }
        }
        a *= 2;
    }
    cout << kotae << endl;

    return 0;
}