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 maxn = 300010;
int n;
char s[maxn], t[maxn], ans[maxn];
int main() {
  scanf("%s %s", s + 1, t + 1), n = strlen(s + 1);
  sort(s + 1, s + n + 1);
  sort(t + 1, t + n + 1);
  int l1 = 1, r1 = n;
  int l2 = 1, r2 = n;
  for (int i = 1, cur = 0; i <= n; i++, cur ^= 1) {
    if (!cur)
      ans[i] = s[l1++];
    else
      ans[i] = t[r2--];
  }
  printf("%s\n", ans + 1);
  return 0;
}
