#include <bits/stdc++.h>
using namespace std;
int main() {
  string n1, n2;
  cin >> n1 >> n2;
  for (int i = 0; i < n1.length(); i++) {
    if (n1[i] == n2[i])
      cout << 0;
    else
      cout << 1;
  }
  return 0;
}
