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 oleg[500];
int igor[500];
char olegs[300100];
char igors[300100];
char res[300100];
int main() {
  cin >> olegs;
  cin >> igors;
  int i;
  for (i = 0; i <= strlen(olegs); i++) {
    oleg[olegs[i]]++;
  }
  for (i = 0; i <= strlen(igors); i++) {
    igor[igors[i]]++;
  }
  int j;
  bool olegC = true;
  for (i = 1; i <= strlen(olegs); i++) {
    if (olegC == true) {
      for (j = 97; j <= 122; j++) {
        if (oleg[j] > 0) {
          res[i] = (char)j;
          oleg[j]--;
          break;
        }
      }
      olegC = false;
    } else {
      for (j = 122; j >= 97; j--) {
        if (igor[j] > 0) {
          res[i] = (char)j;
          igor[j]--;
          break;
        }
      }
      olegC = true;
    }
  }
  cout << string(res + 1, res + 1 + strlen(olegs));
  return 0;
}
