/* -*- coding: utf-8 -*-
 *
 * 2323.cc:  No.2323 Nafmo、A+Bをする - yukicoder
 */

#include<cstdio>
#include<algorithm>
 
using namespace std;

/* constant */

/* typedef */

/* global variables */

/* subroutines */

int readbin() {
  char s[64];
  scanf("%s", s);

  int b = 0;
  for (int i = 0; s[i]; i++) b = (b << 1) | (s[i] - '0');
  return b;
}

/* main */

int main() {
  int a = readbin(), b = readbin();
  printf("%d\n", a ^ b);
  return 0;
}