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 = 300005;
char s1[N], s2[N], s[N];
int main() {
  int len, i, set = 0;
  scanf("%s", s1);
  scanf("%s", s2);
  len = strlen(s1);
  sort(s1, s1 + len);
  sort(s2, s2 + len);
  int len2 = len / 2;
  int len1 = len - len2;
  for (i = 0; i < len2; i++) s2[i] = s2[len - 1 - i];
  int p1 = 0, p2 = 0;
  s1[len1] = '\0';
  s2[len2] = '\0';
  for (i = 0; i < len; i++) {
    if (s1[p1] >= s2[p2]) break;
    if (i % 2 == 0) {
      s[i] = s1[p1++];
    } else {
      s[i] = s2[p2++];
    }
  }
  p1 = len1 - 1;
  p2 = len2 - 1;
  set = len - 1;
  for (; i < len; i++) {
    if (i % 2 == 0) {
      s[set--] = s1[p1--];
    } else {
      s[set--] = s2[p2--];
    }
  }
  printf("%s", s);
  return 0;
}
