#include <bits/stdc++.h>
using namespace std;
map<int, char> mp;
int main() {
  string s1, s2;
  cin >> s1 >> s2;
  sort(s1.begin(), s1.end());
  sort(s2.rbegin(), s2.rend());
  string s3 = "";
  string s4 = "";
  int i1 = 0, i2 = 0;
  for (int i = 0; i < s1.size(); i++) {
    if (i % 2 == 0)
      s3 += s1[i1++];
    else
      s4 += s2[i2++];
  }
  sort(s4.begin(), s4.end());
  int lo = 0, hi = s1.size() - 1;
  int l1 = 0, l2 = 0;
  int c1 = 1;
  int x1 = s3.size();
  int x2 = s4.size();
  for (int c1 = 1; c1 <= s1.size(); c1++) {
    if (c1 % 2) {
      if (s3[l1] < s4[x2 - 1]) {
        mp[lo] = s3[l1];
        l1++;
        lo++;
      } else {
        mp[hi] = s3[x1 - 1];
        x1--;
        hi--;
      }
    } else {
      if (s3[l1] < s4[x2 - 1]) {
        mp[lo] = s4[x2 - 1];
        x2--;
        lo++;
      } else {
        mp[hi] = s4[l2];
        hi--;
        l2++;
      }
    }
  }
  for (int i = 0; i < s1.size(); i++) cout << mp[i];
  cout << endl;
}
