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 N = 300005;
bool cmp(char x, char y) { return x > y; }
char a[N], b[N], c[2 * N];
int main() {
  scanf("%s%s", a, b);
  int la = strlen(a);
  int lb = strlen(b);
  sort(a, a + la);
  sort(b, b + lb, cmp);
  int cnt = 0;
  for (int i = 1; i <= la; ++i, cnt += 2) {
    c[cnt] = a[i - 1];
    c[cnt + 1] = b[i - 1];
  }
  cnt = min(cnt, la);
  for (int i = 0; i < cnt; ++i) printf("%c", c[i]);
  puts("");
  return 0;
}
