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() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  string o, i, ans = "";
  cin >> o >> i;
  long long as = 0, ae = o.length() - 1;
  for (long long k = 0; k < ae + 1; ++k) ans += '?';
  sort(o.begin(), o.end());
  long long os = 0, oe = (o.length() + 1) / 2 - 1;
  sort(i.begin(), i.end(), greater<char>());
  long long is = 0, ie = (i.length() - 1) / 2 - 1, n = ae + 1;
  for (long long k = 0; k < n; ++k)
    if (o[os] < i[is])
      ans[as++] = (k & 1 ? i[is++] : o[os++]);
    else
      ans[ae--] = (k & 1 ? i[ie++] : o[oe--]);
  cout << ans << endl;
  return 0;
}
