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;
bool cmp(char a, char b) { return a > b; }
int main() {
  string a;
  string b;
  cin >> a >> b;
  sort(a.begin(), a.end());
  sort(b.begin(), b.end(), cmp);
  bool a_turn = a[0] > b[0];
  string ret = "";
  int a_idx = 0;
  int b_idx = 0;
  for (int i = 0; i < b.size(); i++) {
    ret += a_turn ? a[a_idx++] : b[b_idx++];
    a_turn = !a_turn;
  }
  cout << ret << endl;
}
