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;
string s, t;
int main() {
  cin >> s >> t;
  int n = s.length();
  sort(s.begin(), s.end());
  sort(t.begin(), t.end());
  reverse(t.begin(), t.end());
  string z = s;
  int l = 0, r = n - 1, l1 = 0, r1 = (n + 1) / 2, l2 = 0, r2 = n / 2;
  for (int i = 0; i < n; ++i) {
    if (i % 2 == 0) {
      if (l2 < n && s[l1] >= t[l2]) {
        z[r] = s[r1 - 1];
        r--;
        r1--;
      } else {
        z[l] = s[l1];
        l++;
        l1++;
      }
    } else {
      if (l1 < n && s[l1] >= t[l2]) {
        z[r] = t[r2 - 1];
        r--;
        r2--;
      } else {
        z[l] = t[l2];
        l++;
        l2++;
      }
    }
  }
  cout << z;
  return 0;
}
