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 int mod = 1e9 + 7;
const long long INF = 1e9 + 7;
const int N = 1010;
const double pi = 3.1415926;
string s1, s2;
char str[300010];
bool cmp(char a, char b) { return a > b; }
int main() {
  freopen("C://Users//Ёбнд©║//Desktop//in.txt", "r", stdin);
  ;
  cin >> s1 >> s2;
  sort(s1.begin(), s1.end());
  sort(s2.begin(), s2.end(), cmp);
  int len = s1.length();
  int l1 = 0, l2 = 0, r1 = (len + 1) / 2 - 1, r2 = len / 2 - 1, l = 0,
      r = len - 1;
  for (int i = 0; i < len; i++) {
    if (s1[l1] >= s2[l2]) {
      if (i % 2 == 0) {
        str[r--] = s1[r1--];
      } else
        str[r--] = s2[r2--];
    } else {
      if (i % 2 == 0) {
        str[l++] = s1[l1++];
      } else
        str[l++] = s2[l2++];
    }
  }
  str[len] = '\0';
  printf("%s\n", str);
  return 0;
}
