#include <bits/stdc++.h>
using namespace std;
long long int ans;
int arr[300009];
vector<int> vr;
void solve() {
  string s1, s2;
  cin >> s1 >> s2;
  for (int i = 0; s1[i] != '\0'; ++i) {
    int x = s1[i] - 48;
    int y = s2[i] - 48;
    int z = x ^ y;
    cout << z;
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int testc;
  testc = 1;
  for (int t = 0; t < testc; ++t) {
    solve();
  }
  return 0;
}
