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