#include <iostream>
#include <cassert>
#include <algorithm>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  string A, B; cin >> A >> B;
  reverse(A.begin(), A.end());
  reverse(B.begin(), B.end());
  if (A.size() < B.size()) swap(A, B);
  int m = B.size();
  int ans = 0;
  for (int i = 0; i < m; i++) {
    int x = 1;
    if (A[i] == B[i]) x = 0;
    if (x == 1) ans += 1 << i;
  }
  for (int i = m; i < A.size(); i++) {
    if (A[i] == '1') ans += 1 << i;
  }
  cout << ans << endl;
  return 0;
}