bcdef
abbbc
 z
y
 reddit
abcdef
 abc
aaa
 y
z
 cbxz
aaaa

bccdb
 z
 dfdeed
 aab
 y
 abac

#include <bits/stdc++.h>
const int maxn = 300000 + 5;
using namespace std;
int main() {
  string s, t, ans;
  s.clear();
  t.clear();
  ans.clear();
  cin >> s >> t;
  int l = s.length();
  for (int i = 0; i < l; i++) ans.push_back('?');
  int c = 0;
  sort(s.begin(), s.end());
  sort(t.begin(), t.end());
  int rt = 0;
  int tr = l - 1;
  int cc = l - 1;
  int bb = 0;
  int gg, hh;
  if (l & 1) {
    gg = (l - 1) / 2;
    hh = gg + 1;
  } else {
    gg = l / 2 - 1;
    hh = gg + 1;
  }
  while (c < l) {
    if (c & 1) {
      if (s[rt] < t[tr])
        ans[bb++] = t[hh++];
      else
        ans[cc--] = t[tr--];
    } else {
      if (s[rt] > t[l - 1])
        ans[cc--] = s[gg--];
      else
        ans[bb++] = s[rt++];
    }
    c++;
  }
  cout << ans;
  return 0;
}
