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