#include <bits/stdc++.h>
using namespace std;
string a;
string b;
string ans = "";
int main() {
  cin >> a;
  cin >> b;
  int len = a.size();
  sort(a.begin(), a.end());
  sort(b.begin(), b.end());
  reverse(b.begin(), b.end());
  int p = 0;
  int q = 0;
  int p_end;
  int q_end;
  if (len % 2 == 0) {
    p_end = (len / 2) - 1;
    q_end = p_end;
  } else {
    p_end = (len - 1) / 2;
    q_end = p_end - 1;
  }
  ans = a;
  int start = 0;
  int end = len - 1;
  char best_a = a[0];
  char worst_a = a[len - 1];
  char best_b = b[0];
  char worst_b = b[len - 1];
  for (int i = 0; i < len; i++) {
    if (i % 2 == 0) {
      if (best_b <= best_a) {
        ans[end] = a[p_end];
        end--;
        p_end--;
        best_a = ((best_a < a[p_end]) ? best_a : a[p_end]);
      } else {
        ans[start] = a[p];
        start++;
        p++;
        best_a = a[p];
      }
    } else {
      if (best_b <= best_a) {
        ans[end] = b[q_end];
        end--;
        q_end--;
        best_b = ((best_b > b[q_end]) ? best_b : b[q_end]);
      } else {
        ans[start] = b[q];
        start++;
        q++;
        best_b = b[q];
      }
    }
  }
  cout << ans << "\n";
  return 0;
}
