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;
char arr1[300005], arr2[300005];
int main() {
  int i, l;
  string s1, s2, s = "", s3 = "";
  cin >> s1 >> s2;
  l = s1.length();
  for (i = 0; i < l; i++) {
    arr1[i] = s1[i];
    arr2[i] = s2[i];
  }
  sort(arr1, arr1 + l);
  sort(arr2, arr2 + l);
  for (i = 0; i <= l / 2; i++) {
    s += arr1[i];
    s += arr2[l - i - 1];
  }
  for (i = 0; i < l; i++) {
    printf("%c", s[i]);
  }
  return 0;
}
