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