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() {
  long long n;
  string s1, s2;
  multiset<char> f, s;
  cin >> s1 >> s2;
  n = s1.size();
  for (long long i = 0; i < s1.size(); i++) {
    f.insert(s1[i]);
  }
  for (long long i = 0; i < s1.size(); i++) {
    s.insert(s2[i]);
  }
  for (long long i = 1; i <= n; i++) {
    if (i % 2) {
      cout << *f.begin();
      f.erase(f.begin());
    } else {
      char ch = *(--s.end());
      cout << ch;
      s.erase(--s.end());
    }
  }
  return 0;
}
