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 s[2][1000005];
bool complare1(char a, char b) { return a < b; }
bool complare2(char a, char b) { return a > b; }
int main() {
  int t = 0, len, top[3];
  cin >> s[0] >> s[1];
  len = strlen(s[0]);
  sort(s[0], s[0] + len, complare1);
  sort(s[1], s[1] + len, complare2);
  top[0] = top[1] = 0;
  while (len > 0) {
    cout << s[t % 2][top[t % 2]];
    top[t % 2]++;
    t++;
    len--;
  }
  return 0;
}
