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;
const int N = int(3e5) + 10, mod = int(1e9) + 7;
int ca[30], cb[30], xa[30], xb[30];
char second[N];
int t[4 * N];
void update(int v, int tl, int tr, int pos) {
  if (tl == tr) {
    t[v] = 0;
    return;
  }
  int tm = (tl + tr) / 2;
  if (pos <= tm) {
    update(v + v, tl, tm, pos);
  } else {
    update(v + v + 1, tm + 1, tr, pos);
  }
  t[v] = t[v + v] + t[v + v + 1];
}
int get(int v, int tl, int tr, int k) {
  if (tl == tr) return tl;
  int tm = (tl + tr) / 2;
  if (t[v + v] >= k) {
    return get(v + v, tl, tm, k);
  }
  return get(v + v + 1, tm + 1, tr, k - t[v + v]);
}
void build(int v, int tl, int tr) {
  if (tl == tr) {
    t[v] = 1;
    return;
  }
  int tm = (tl + tr) / 2;
  build(v + v, tl, tm);
  build(v + v + 1, tm + 1, tr);
  t[v] = t[v + v] + t[v + v + 1];
}
vector<char> va, vb;
int main() {
  scanf("%s", second + 1);
  int n = strlen(second + 1);
  for (int i = 1; i <= n; i++) {
    ca[second[i] - 'a']++;
  }
  scanf("\n%s", second + 1);
  for (int i = 1; i <= n; i++) {
    cb[second[i] - 'a']++;
  }
  int k = (n + 1) / 2;
  for (int i = 0; i < 26; i++) {
    ca[i] = min(ca[i], k);
    k -= ca[i];
  }
  k = n / 2;
  for (int j = 25; j >= 0; j--) {
    cb[j] = min(cb[j], k);
    k -= cb[j];
  }
  int res = 0;
  for (int i = 1; i <= n; i++) {
    if (i & 1) {
      int first = 0;
      for (int j = 0; j < 26; j++) {
        if (ca[j]) {
          first = j;
          break;
        }
      }
      bool ok = 0;
      int cnt = 0;
      for (int j = 0; j < 26; j++) {
        if (cb[j] && j > first) {
          ok = 1;
        }
        cnt += cb[j];
      }
      if (ok) {
        second[++res] = char(first + 'a');
        ca[first]--;
      } else {
        for (int j = 0; j < 26; j++) {
          for (int k = 0; k < ca[j]; k++) {
            va.push_back(char(j + 'a'));
          }
        }
        for (int j = 25; j >= 0; j--) {
          for (int k = 0; k < cb[j]; k++) {
            vb.push_back(char(j + 'a'));
          }
        }
        for (int j = 0; j < vb.size(); j++) {
          second[++res] = vb[j];
          second[++res] = va[j];
        }
        if (va.size() > vb.size()) {
          second[++res] = va[int(va.size()) - 1];
        }
        break;
      }
    } else {
      int first = 0;
      for (int j = 0; j < 26; j++) {
        if (cb[j]) {
          first = j;
        }
      }
      bool ok = 0;
      for (int j = 0; j < 26; j++) {
        if (ca[j] && j < first) {
          ok = 1;
        }
      }
      if (ok) {
        cb[first]--;
        second[++res] = char(first + 'a');
      } else {
        for (int j = 0; j < 26; j++) {
          for (int k = 0; k < ca[j]; k++) {
            va.push_back(char(j + 'a'));
          }
        }
        for (int j = 25; j >= 0; j--) {
          for (int k = 0; k < cb[j]; k++) {
            vb.push_back(char(j + 'a'));
          }
        }
        for (int j = 0; j < va.size(); j++) {
          second[++res] = va[j];
          if (j < vb.size()) second[++res] = vb[j];
        }
        break;
      }
    }
  }
  printf("%s", second + 1);
  return 0;
}
