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