#include <bits/stdc++.h>
using namespace std;
int main() {
  string s1, s2;
  cin >> s1 >> s2;
  for (size_t i = 0; i < s1.length(); ++i) {
    if (s1[i] == s2[i]) {
      s1[i] = '0';
    } else {
      s1[i] = '1';
    }
  }
  cout << s1 << endl;
  return 0;
}
