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() {
  int n;
  string a_, b_, c;
  cin >> a_ >> b_;
  n = int(a_.size());
  char a[n], b[n];
  for (int i = 0; i < n; i++) {
    a[i] = a_[i];
    b[i] = b_[i];
  }
  sort(a, a + n);
  sort(b, b + n);
  int i1 = 0, i2 = n - 1;
  for (int i = 0; i < n; i++) {
    if (i % 2 == 0) {
      c += a[i1++];
    } else {
      c += b[i2--];
    }
  }
  cout << c << "\n";
}
