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 a[300010], b[300010], temp[300010];
int main() {
  cin >> a >> b;
  int lon = strlen(a);
  sort(a, a + lon);
  sort(b, b + lon);
  int i = 0, j = 0, k = lon - 1, t = 0, _i = lon - 1, _j = (lon + 1) / 2 - 1,
      _k = (lon + 1) / 2;
  while (t < lon) {
    if (a[j] >= b[k]) {
      break;
    }
    if (t % 2 == 0) {
      temp[i++] = a[j++];
    } else {
      temp[i++] = b[k--];
    }
    t++;
  }
  while (t < lon) {
    if (t % 2 == 0) {
      temp[_i--] = a[_j--];
    } else {
      temp[_i--] = b[_k++];
    }
    t++;
  }
  cout << temp << endl;
}
