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;
bool cmp(const char &a, const char &b) { return a > b; }
const int N = 3 * 1e5 + 20;
char a[N], b[N], c[N];
int main() {
  while (~scanf("%s%s", a, b)) {
    int len = strlen(a);
    c[len] = '\0';
    sort(a, a + len);
    sort(b, b + len, cmp);
    int x = len;
    int blen = len / 2 - 1;
    int alen = (len + 1) / 2 - 1;
    int la = 0, lb = 0;
    int ra = alen, rb = blen, l = 0, r = len - 1;
    int k = 1;
    while (x--) {
      if (k % 2) {
        if ((la == ra)) {
          c[l++] = a[la];
        } else if (a[la] >= b[lb]) {
          c[r--] = a[ra--];
        } else {
          c[l++] = a[la++];
        }
      } else {
        if ((lb == rb)) {
          c[l++] = b[lb];
        } else if (a[la] < b[lb]) {
          c[l++] = b[lb++];
        } else {
          c[r--] = b[rb--];
        }
      }
      k++;
    }
    cout << c;
    cout << endl;
  }
  return 0;
}
