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() {
  int n;
  string oleg, igor;
  char ans[1000050];
  getline(cin, oleg);
  getline(cin, igor);
  n = oleg.size();
  sort(oleg.begin(), oleg.end());
  sort(igor.rbegin(), igor.rend());
  int st = 0, en = n - 1, o_st = 0, i_st = 0, o_en = (n + 1) / 2 - 1,
      i_en = n / 2 - 1;
  for (int i = 0; i < n; ++i) {
    if (i & 1) {
      if (oleg[o_st] < igor[i_st])
        ans[st++] = igor[i_st++];
      else
        ans[en--] = igor[i_en--];
    } else {
      if (oleg[o_st] < igor[i_st])
        ans[st++] = oleg[o_st++];
      else
        ans[en--] = oleg[o_en--];
    }
  }
  for (int i = 0; i < n; ++i) printf("%c", ans[i]);
  cout << endl;
  return 0;
}
