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 = 3e5 + 10;
int n, i1, i2, g, h, f, k;
string x, z, ans;
int main() {
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(2);
  cin >> x >> z;
  sort(x.begin(), x.end());
  sort(z.begin(), z.end());
  reverse(z.begin(), z.end());
  n = x.size();
  i1 = (n - 1) / 2;
  i2 = (n - 2) / 2;
  for (int i = 0; i < n; i++) ans += ' ';
  g = n - 1;
  for (int i = 0; i < n; i++) {
    if (x[i] < z[i]) {
      ans[f++] = x[i];
    } else {
      ans[g--] = x[i1--];
    }
    k++;
    if (k >= n) break;
    if (x[i + 1] < z[i]) {
      ans[f++] = z[i];
    } else {
      ans[g--] = z[i2--];
    }
    k++;
    if (k >= n) break;
  }
  cout << ans;
  return 0;
}
