#include <bits/stdc++.h>
using namespace std;
int main() {
  string n, m;
  cin >> n;
  cin >> m;
  string ans = "";
  for (int i = 0; i < n.size(); i++) {
    if (n[i] != m[i])
      ans += "1";
    else
      ans += "0";
  }
  cout << ans;
  return 0;
}
