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;
char s1[300005], s2[300005];
bool r1(char a, char b) { return (a <= b); }
bool r2(char a, char b) { return (a >= b); }
int main() {
  cin >> s1;
  cin >> s2;
  int n = strlen(s1), cnt = 0;
  sort(s1, s1 + n, r1);
  sort(s2, s2 + n, r2);
  for (int i = 0; cnt < n; i += 2) {
    char a = s1[i / 2];
    char b = s2[i / 2];
    if (a <= b) {
      cout << a;
      cnt++;
      if (cnt == n) break;
      cout << b;
      cnt++;
    } else {
      cout << b;
      cnt++;
      if (cnt == n) break;
      cout << a;
      cnt++;
    }
  }
}
