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() {
  ios_base::sync_with_stdio(0);
  string s1;
  string s2;
  cin >> s1;
  cin >> s2;
  unordered_map<char, int> oleg;
  unordered_map<char, int> igor;
  vector<char> chars;
  for (int i = 0; i < 26; i++) {
    chars.push_back('a' + i);
    oleg[chars[i]] = 0;
    igor[chars[i]] = 0;
  }
  int n = s1.size();
  for (char c : s1) {
    oleg[c]++;
  }
  for (char c : s2) {
    igor[c]++;
  }
  int oleg_pointer = 0;
  int igor_pointer = 25;
  vector<char> output(n);
  for (int i = 0; i < n; i++) {
    if (i % 2 == 0) {
      while (oleg[chars[oleg_pointer]] == 0) oleg_pointer++;
      oleg[chars[oleg_pointer]]--;
      output[i] = chars[oleg_pointer];
    } else {
      while (igor[chars[igor_pointer]] == 0) igor_pointer--;
      igor[chars[igor_pointer]]--;
      output[i] = chars[igor_pointer];
    }
  }
  for (int i = 0; i < n; i++) {
    cout << output[i];
  }
  cout << endl;
  return 0;
}
