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() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  string a, b;
  cin >> a >> b;
  int l = a.length();
  sort(a.begin(), a.end());
  sort(b.begin(), b.end(), greater<char>());
  a.resize((l + 1) / 2);
  b.resize(l / 2);
  char ans[l + 1];
  int i = 0, j = 0, ls = 0, rs = l - 1;
  for (int cnt = 0; cnt < l; cnt++) {
    if (cnt % 2 == 0) {
      if (a[i] < b[j])
        ans[ls++] = a[i], i++;
      else {
        ans[rs--] = a.back();
        a.pop_back();
      }
    } else {
      if (b[j] > a[i])
        ans[ls++] = b[j], j++;
      else {
        ans[rs--] = b.back();
        b.pop_back();
      }
    }
  }
  for (int i = 0; i < l; i++) cout << ans[i];
  return 0;
}
