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;
#pragma GCC optimize("O3")
char a[500000];
signed main() {
  string st1, st2;
  cin >> st1 >> st2;
  long long n = st1.size();
  sort(st1.begin(), st1.end());
  sort(st2.begin(), st2.end());
  reverse(st2.begin(), st2.end());
  while (st1.size() > (n + 1) / 2) st1.pop_back();
  while (st2.size() > (n) / 2) st2.pop_back();
  long long last1 = 0;
  long long last2 = 0;
  long long last = 1;
  long long llast1 = n - (st1.size() - last1) + 1;
  long long llast2 = n - (st2.size() - last2) + 1;
  for (long long i = 1; i <= n; i++) a[i] = ' ';
  for (long long i = 1; i <= n; i++) {
    if (i % 2 == 1) {
      if (st1[last1] >= st2[last2]) {
        while (a[llast1] != ' ') llast1++;
        if (llast1 > n) llast1 = last;
        while (a[llast1] != ' ') llast1++;
        a[llast1] = st1[last1];
        llast1++;
      } else {
        while (a[last] != ' ') last++;
        a[last] = st1[last1];
        last++;
      }
      last1++;
    } else {
      if (st2[last2] <= st1[last1]) {
        while (a[llast2] != ' ') llast2++;
        if (llast2 > n) llast2 = last;
        while (a[llast2] != ' ') llast2++;
        a[llast2] = st1[last2];
        llast2++;
      } else {
        while (a[last] != ' ') last++;
        a[last] = st2[last2];
        last++;
      }
      last2++;
    }
  }
  for (long long i = 1; i <= n; i++) cout << a[i];
}
