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 INF = 0x3f3f3f3f;
const long long LINF = 0x3f3f3f3f3f3f3f3f;
template <typename T, typename T2>
inline void _max(T &a, T2 b) {
  a = max((T)a, (T)b);
}
template <typename T, typename T2>
inline void _min(T &a, T2 b) {
  a = min((T)a, (T)b);
}
const int MAX = 3e5 + 100;
char s1[MAX], s2[MAX], res[MAX];
int n;
void clear() { memset(res, 0, sizeof(res)); }
void read() {}
void solve() {
  n = strlen(s1);
  if (n == 1) return void(printf("%s\n", s1));
  sort(s1, s1 + n);
  sort(s2, s2 + n, [](const char &a, const char &b) -> bool { return a > b; });
  int l1 = 0, r1 = (n + 1) / 2 - 1, l2 = 0, r2 = n / 2 - 1, l = 0, r = n - 1;
  int turn = 0;
  for (int i = 0; i < n; i++) {
    if (turn) {
      if (s1[l1] > s2[l2])
        res[r--] = s2[r2--];
      else
        res[l++] = s2[l2++];
    } else {
      if (s1[l1] > s2[l2])
        res[r--] = s1[r1--];
      else
        res[l++] = s1[l1++];
    }
    turn ^= 1;
  }
  printf("%s\n", res);
}
int main() {
  while (scanf("%s%s", s1, s2) == 2) {
    clear();
    read();
    solve();
    return 0;
  }
  return 0;
}
