#include <bits/stdc++.h>
using namespace std;
void solve() {
  string a, b, c = "";
  cin >> a >> b;
  int n = a.length();
  for (int i = n - 1; i >= 0; i--) {
    if (a[i] == b[i])
      c += "0";
    else
      c += "1";
  }
  reverse(c.begin(), c.end());
  cout << c;
}
int main() {
  solve();
  return 0;
}
