#include <bits/stdc++.h>
using namespace std;
int main() {
  string a, b, rez;
  cin >> a >> b;
  for (int i = 0; i < a.size(); ++i) {
    rez += (a[i] == b[i] ? "0" : "1");
  }
  cout << rez;
  return 0;
}
