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;
int main() {
  char ch[300001], cha[300001];
  int i, j, len, cnt = 0;
  scanf("%s", ch);
  scanf("%s", cha);
  len = strlen(ch);
  sort(ch, ch + len);
  sort(cha, cha + len);
  i = 0;
  j = len - 1;
  while (i <= (len - 1) / 2 && j >= (len - 1) / 2) {
    if (j == (len - 1) / 2) {
      printf("%c", ch[i]);
      j--;
    } else if (ch[i] <= cha[j]) {
      printf("%c%c", ch[i], cha[j]);
      i++;
      j--;
    } else {
      printf("%c", cha[j]);
      j--;
      while (i <= (len - 1) / 2) {
        printf("%c", ch[i]);
        i++;
      }
      while (j > (len - 1) / 2) {
        printf("%c", cha[j]);
        j--;
      }
      break;
    }
  }
  return 0;
}
