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 s1, s2;
  cin >> s1 >> s2;
  sort(s1.begin(), s1.end());
  sort(s2.rbegin(), s2.rend());
  string s = "";
  int n = s1.size();
  for (int i = 0; i < n; i++) {
    s += '#';
  }
  deque<char> q1, q2;
  for (int i = 0; i < (n + 1) / 2; i++) {
    q1.push_back(s1[i]);
  }
  for (int i = 0; i < n / 2; i++) {
    q2.push_back(s2[i]);
  }
  int first_pointer = 0;
  int last_pointer = n - 1;
  for (int i = 0; i < n; i++) {
    if (i % 2 == 0) {
      if (q1[0] >= q2[0]) {
        s[last_pointer] = q1.back();
        last_pointer--;
        q1.pop_back();
      } else {
        s[first_pointer] = q1[0];
        first_pointer++;
        q1.pop_front();
      }
    } else {
      if (q1[0] >= q2[0]) {
        s[last_pointer] = q2.back();
        last_pointer--;
        q2.pop_back();
      } else {
        s[first_pointer] = q2[0];
        first_pointer++;
        q2.pop_front();
      }
    }
  }
  cout << s << "\n";
  return 0;
}
