#include <bits/stdc++.h>
int main() {
  char a[101], b[101];
  scanf("%s%s", a, b);
  for (int i = 0; a[i] != '\0'; i++) {
    if ((a[i] == '1' && b[i] == '1') || (a[i] == '0' && b[i] == '0'))
      printf("0");
    else
      printf("1");
  }
}
