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 x[100005];
map<int, int> h;
vector<char> ar;
vector<char> ar1;
int main() {
  ios_base::sync_with_stdio(false);
  int i;
  string s1, s2;
  cin >> s1 >> s2;
  int n = s1.size();
  for (i = 0; i < n; i++) {
    ar.push_back(s1[i]);
    ar1.push_back(s2[i]);
  }
  sort(ar.begin(), ar.end());
  sort(ar1.begin(), ar1.end());
  int j = n - 1;
  int k = 0;
  int flag = 1;
  for (i = 0; i < n; i++) {
    if (flag) {
      cout << ar[k];
      k++;
    } else {
      cout << ar1[j];
      j--;
    }
    flag = 1 - flag;
  }
  cout << "\n";
}
