bcdef
abbbc
 z
y
 reddit
abcdef
 abc
aaa
 y
z
 cbxz
aaaa

bccdb
 z
 dfdeed
 aab
 y
 abac

#include <bits/stdc++.h>
using namespace std;
const int N = 300300;
char a[N], b[N], s[N];
int n;
int main() {
  scanf("%s", a);
  scanf("%s", b);
  n = strlen(a);
  sort(a, a + n);
  sort(b, b + n);
  reverse(b, b + n);
  int i = 0, j = 0;
  int ii = ((n + 1) / 2) - 1, jj = (n / 2) - 1;
  int st = 0, en = n - 1;
  for (int k = 0; k < n; k++) {
    if (1 - (k & 1)) {
      if (b[j] <= a[i]) {
        s[en--] = a[ii--];
      } else {
        s[st++] = a[i++];
      }
    } else {
      if (b[j] <= a[ii]) {
        s[en--] = b[jj--];
      } else {
        s[st++] = b[j++];
      }
    }
  }
  for (int i = 0; i < n; i++) printf("%c", s[i]);
  printf("\n");
  return 0;
}
