#include <bits/stdc++.h>
using namespace std;
string s;
int main() {
  string a, b;
  cin >> a >> b;
  string ans = "";
  for (int i = 0; i < a.length(); i++) {
    if (a[i] == '1' && b[i] == '1' || a[i] == '0' && b[i] == '0') {
      ans += '0';
    } else
      ans += '1';
  }
  cout << ans;
  return 0;
}
