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 ans[345678];
signed main() {
  int n, id = 0, fl = 0, num = 0;
  string s, t;
  cin >> s >> t;
  n = s.length();
  int op = n / 2 + n % 2, k1 = 0, k2 = 0;
  sort(s.begin(), s.end());
  while (s.size() != op) s.pop_back();
  op = n - op;
  sort(t.rbegin(), t.rend());
  while (t.size() != op) t.pop_back();
  while (ans[id] == 0 && id < n) {
    if (num % 2 == 0) {
      if (s[k1] < t[k2]) {
        ans[id++] = s[k1];
        num++;
        k1++;
      } else {
        if (!fl) {
          id = n - 1;
          fl = 1;
          k1 = s.length() - 1;
          k2 = t.length() - 1;
        }
        ans[id--] = s[k1--];
        num++;
      }
    } else {
      if (t[k2] > s[k1]) {
        ans[id++] = t[k2];
        num++;
        k2++;
      } else {
        if (!fl) {
          id = n - 1;
          fl = 1;
          k1 = s.length() - 1;
          k2 = t.length() - 1;
        }
        ans[id--] = t[k2--];
        num++;
      }
    }
  }
  ans[n] = '\0';
  printf("%s\n", ans);
}
