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;
char now1[1000010], now2[1000010], re[1000010];
int cmp(int a, int b) { return a > b; }
int main() {
  scanf("%s", now1);
  int cnt = 0;
  for (int i = 0; now1[i] != '\0'; i++) cnt++;
  scanf("%s", now2);
  sort(now1, now1 + cnt);
  sort(now2, now2 + cnt, cmp);
  int sum1 = cnt / 2 - 1, sum2 = cnt / 2 - 1, pos1 = 0, pos2 = 0, pos = cnt - 1,
      poss = 0;
  if (cnt % 2 == 1) sum1 += 1;
  int k = 0;
  while (1) {
    k++;
    if (k == cnt + 1) break;
    char c, d;
    if (k % 2 == 1) {
      c = now1[pos1];
      d = now1[sum1];
      if (c < now2[pos2]) {
        pos1++;
        re[poss++] = c;
      } else {
        sum1--;
        re[pos--] = d;
      }
    } else {
      c = now2[pos2];
      d = now2[sum2];
      if (now1[pos1] < c) {
        pos2++;
        re[poss++] = c;
      } else {
        sum2--;
        re[pos--] = d;
      }
    }
  }
  for (int i = 0; i < cnt - 1 + 1; i++) printf("%c", re[i]);
  return 0;
}
