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;
int main() {
  string a, b;
  cin >> a >> b;
  sort(a.begin(), a.end());
  sort(b.begin(), b.end());
  reverse(b.begin(), b.end());
  string n;
  for (int i = 0; i < a.size() / 2; i++) {
    if (a[i] < b[i]) {
      n += a[i];
      n += b[i];
    } else {
      n += b[i];
      n += a[i];
    }
  }
  if (a.size() % 2 != 0) {
    n += a[a.size() / 2];
  }
  cout << n;
}
