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;
const long long int INF = 1e18;
const int inf = 1e9;
const int MOD = 1e9 + 7;
const int nax = 1000000 + 10;
char arr[nax];
vector<char> oleg, igor;
int main() {
  ios::sync_with_stdio(0);
  string s1, s2;
  int len;
  cin >> s1 >> s2;
  len = s1.length();
  sort(s1.begin(), s1.end());
  sort(s2.begin(), s2.end());
  reverse(s2.begin(), s2.end());
  int n1, n2;
  if (len % 2 == 0) {
    n1 = len / 2;
    n2 = len / 2;
  } else {
    n1 = len / 2 + 1;
    n2 = len / 2;
  }
  s2 = s2.substr(0, n2);
  reverse(s2.begin(), s2.end());
  int left1 = 0, left2 = 0;
  int right1 = n1 - 1;
  int right2 = n2 - 1;
  int left = 0, right = len - 1;
  for (int i = 1; i <= len; i++) {
    if (i % 2 == 0) {
      if (s1[left1] > s2[right2]) {
        arr[right--] = s2[left2++];
      } else {
        arr[left++] = s2[right2--];
      }
    } else {
      if (s2[right2] < s1[left1]) {
        arr[right--] = s1[right1--];
      } else {
        arr[left++] = s1[left1++];
      }
    }
  }
  for (int i = 0; i < len; i++) cout << arr[i];
  return 0;
}
