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;
  string s;
  cin >> s1 >> s2;
  sort(s1.begin(), s1.end());
  sort(s2.begin(), s2.end());
  long int n = s1.length();
  long int j1 = 0, j2 = n - 1;
  for (long int i = 0; i < n; i++) {
    if (i % 2 == 0) {
      s = s + s1[j1];
      j1++;
    } else {
      s = s + s2[j2];
      j2--;
    }
  }
  cout << s << endl;
  return 0;
}
