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 string TASK = "";
int n, i;
string s, t, res;
void Enter() { cin >> s >> t; }
void Solve() {
  sort(s.begin(), s.end());
  sort(t.rbegin(), t.rend());
  int n = s.size();
  s.erase(n - n / 2, n / 2);
  t.erase(n / 2, n - n / 2);
  for (i = 0; i < t.size(); ++i)
    if (s[i] <= t[i]) {
      res.push_back(s[i]);
      res.push_back(t[i]);
    } else
      break;
  for (; i < t.size(); ++i) {
    res.push_back(t[i]);
    res.push_back(s[i]);
  }
  if (i < s.size()) res.push_back(s[i]);
  cout << res;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  Enter();
  Solve();
}
