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;
  int n = a.length();
  string c = a;
  sort(a.begin(), a.end());
  sort(b.begin(), b.end());
  int i = 0, j = (n - 1) / 2;
  int k = j + 1, l = n - 1;
  int bw = 0, fw = n - 1, p = 0;
  while (bw <= fw) {
    if (p & 1) {
      if (b[l] > a[j])
        c[bw] = b[l], l--, bw++;
      else
        c[fw] = b[k], k++, fw--;
    } else {
      if (a[i] < b[k])
        c[bw] = a[i], i++, bw++;
      else
        c[fw] = a[j], j--, fw--;
    }
    p++;
  }
  cout << c << endl;
}
