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;
#pragma GCC optimize("O3")
char a[500000];
signed main() {
  string st1, st2;
  cin >> st1 >> st2;
  long long n = st1.size();
  sort(st1.begin(), st1.end());
  sort(st2.begin(), st2.end());
  reverse(st2.begin(), st2.end());
  while (st1.size() > (n + 1) / 2) st1.pop_back();
  while (st2.size() > (n) / 2) st2.pop_back();
  long long s1 = 0;
  long long s2 = 0;
  long long f1 = st1.size() - 1;
  long long f2 = st2.size() - 1;
  long long s = 0;
  long long f = n - 1;
  for (long long i = 1; i <= n; i++)
    if (i % 2 == 1) {
      if (st1[s1] >= st2[s2]) {
        a[f] = st1[f1];
        f1--;
        f--;
      } else {
        a[s] = st1[s1];
        s1++;
        s++;
      }
    } else {
      if (st1[s1] >= st2[s2]) {
        a[f] = st2[f2];
        f2--;
        f--;
      } else {
        a[s] = st2[s2];
        s2++;
        s++;
      }
    }
  for (long long i = 0; i < n; i++) cout << a[i];
}
