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() {
  string a, b;
  cin >> a >> b;
  long long int n = a.size();
  sort(a.begin(), a.end());
  sort(b.rbegin(), b.rend());
  long long int sa = (n + 1) / 2;
  long long int sb = n - sa;
  a = a.substr(0, sa);
  b = b.substr(0, sb);
  sa--;
  sb--;
  string s = "?";
  for (long long int i = 1; i < n; i++) s += "?";
  long long int j = 0, k = 0;
  long long int i = 0;
  long long int turn = 0;
  for (i = 0; i < n - 1; i++, turn ^= 1) {
    if (turn == 0) {
      if (a[j] < b[k]) {
        s[i] = a[j];
        j++;
      } else {
        break;
      }
    } else {
      if (a[j] < b[k]) {
        s[i] = b[k];
        k++;
      } else {
        break;
      }
    }
  }
  i--;
  {
    long long int ii = n - 1;
    j = sa, k = sb;
    while (ii > i) {
      if (turn == 0) {
        s[ii] = a[j];
        j--;
      } else {
        s[ii] = b[k];
        k--;
      }
      turn ^= 1;
      ii--;
    }
  }
  cout << s << endl;
}
