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 oleg, lgor;
  char finally[300010];
  cin >> oleg >> lgor;
  sort(oleg.begin(), oleg.end());
  sort(lgor.begin(), lgor.end());
  int length = oleg.length(), i, j, l = 0, r = length - 1, dice = 1;
  int l1 = 0, r1 = length - 1;
  finally[length] = '\0';
  while (dice <= length) {
    if (dice % 2 == 1) {
      if (oleg[l] >= lgor[r]) {
        finally[r1--] = oleg[l + (length - dice) / 2];
      } else
        finally[l1++] = oleg[l++];
    } else {
      if (oleg[l] >= lgor[r])
        finally[r1--] = lgor[r - (length - dice) / 2];
      else
        finally[l1++] = lgor[r--];
    }
    dice++;
  }
  cout << finally << '\n';
  return 0;
}
