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;
long long n, m;
bool test = true;
long long const N = 200001;
vector<long long> v1;
vector<double> v;
vector<pair<long long, long long> > vv;
map<double, long long> my;
priority_queue<long long> q;
long long t[N];
long long dx[4] = {0, 1, 0, -1};
long long dy[4] = {1, 0, -1, 0};
bool solve(long long a, long long b, long long x, long long y, long long h,
           long long g) {
  double d = (y - b) / (x - a);
  double d1 = (y - g) / (x - h);
  return d == d1;
}
bool in_da_prison(long long x, long long y) {
  return (x < 9 && x >= 0 && y < 9 && y >= 0);
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long i = 0, j = 0, a = 0, b = 0, c = 0, k = 0, h;
  string s1, s2;
  double d, s, d3, d1;
  cin >> s1 >> s2;
  sort(s1.begin(), s1.end());
  sort(s2.begin(), s2.end());
  a = 0;
  b = s1.size() - 1;
  long long a1 = 0, b1 = b;
  string f = s1;
  long long f1 = 0, f2 = s1.size() - 1;
  for (i = 0; i < s1.size(); i++) {
    if (i % 2) {
      if (s2[b1] < s1[a]) {
        f[f2] = s2[a1];
        a1++;
        f2--;
      } else {
        f[f1] = s2[b1];
        b1--;
        f1++;
      }
    } else {
      if (s1[a] > s2[b1]) {
        f[f2] = s1[b];
        b--;
        f2--;
      } else {
        f[f1] = s1[a];
        a++;
        f1++;
      }
    }
  }
  cout << f;
  return 0;
}
