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;
int main(void) {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n;
  string s, t;
  cin >> s >> t;
  n = s.size();
  vector<int> a(n), b(n);
  for (__typeof(n) i = (0) - ((0) > (n)); i != (n) - ((0) > (n));
       i += 1 - 2 * ((0) > (n)))
    a[i] = s[i];
  for (__typeof(n) i = (0) - ((0) > (n)); i != (n) - ((0) > (n));
       i += 1 - 2 * ((0) > (n)))
    b[i] = t[i];
  sort((a).begin(), (a).end());
  sort((b).begin(), (b).end(), greater<int>());
  s = "";
  int af = 0;
  int ab = n - 1;
  int bf = 0;
  int bb = n - 1;
  for (__typeof(n) i = (0) - ((0) > (n)); i != (n) - ((0) > (n));
       i += 1 - 2 * ((0) > (n))) {
    if (i % 2 == 0) {
      if (a[af] > b[bf] && i < n - 1 && (n - i) % 2 == 0) {
        s.push_back(char(b[bf++]));
        s.push_back(char(a[af++]));
        i++;
      } else
        s.push_back(char(a[af++]));
    } else {
      if (a[af] > b[bf] && i < n - 1 && (n - i) % 2 == 0) {
        s.push_back(char(a[af++]));
        s.push_back(char(b[bf++]));
        i++;
      } else
        s.push_back(char(b[bf++]));
    }
  }
  cout << s;
}
