bcdef
abbbc
 z
y
 reddit
abcdef
 abc
aaa
 y
z
 cbxz
aaaa

bccdb
 z
 dfdeed
 aab
 y
 abac

#include <bits/stdc++.h>
#include <iostream>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define speed                     \
    ios_base::sync_with_stdio(0); \
    cin.tie(0);                   \
    cout.tie(0);
#define ll long long
#define ld long double
#define pb push_back
#define mem1(a) memset(a, -1, sizeof(a))
#define mem0(a) memset(a, 0, sizeof(a))
#define setp(x) fixed << setprecision(x)
#define endl "\n"
#define mod 1000000007
#define mod1 998244353
#define ff first
#define ss second
#define MAX 500005
#define N 500005
#define INF 1000000009
#define all(v) v.begin(), v.end()
#define sbit(a) __builtin_popcount(a)
template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef pair<ll, ll> pll;
typedef pair<pll, ll> ppl;
typedef map<ll, ll> mpll;
typedef map<vector<ll>, ll> mpvl;
ll power(ll x, ll y, ll p)
{
    ll res = 1;
    x = x % p;

    if (x == 0)
        return 0;
    while (y > 0)
    {

        if (y & 1)
            res = (res * x) % p;

        y = y >> 1;
        x = (x * x) % p;
    }

    return res;
}
void solve()
{
    string s, t;
    cin >> s >> t;
    multiset<char> ms, mt;
    ll n = s.length();
    for (auto it : s)
    {
        ms.insert(it);
    }
    for (auto it : t)
    {
        mt.insert(it);
    }
    ll red = n / 2;
    while (red)
    {
        ms.erase(--ms.end());
        red--;
    }
    red = (n + 1) / 2;
    while (red)
    {
        mt.erase(--mt.end());
        red--;
    }
    string ans1 = "", ans2 = "";
    ll cnt = 0;
    while (ans1.size() + ans2.size() != n)
    {

        if (cnt % 2 == 0)
        {

            if (!mt.size())
            {
                ans1 += (*ms.begin());
            }
            else
            {
                char bs = (*ms.begin());
                auto it = mt.end();
                it--;
                char et = *it;
                if (bs >= et)
                {
                    auto it2 = ms.end();
                    it2--;
                    ans2 += *it2;
                    ms.erase(it2);
                }
                else
                {
                    ans1 += bs;
                    ms.erase(ms.begin());
                }
            }
        }
        else
        {
            if (!ms.size())
            {
                ans1 += (*mt.begin());
                continue;
            }
            else
            {
                char bs = (*ms.begin());
                auto it = mt.end();
                it--;
                char et = *it;
                if (et <= bs)
                {
                    ans2 += (*mt.begin());
                    mt.erase(mt.begin());
                }
                else
                {
                    ans1 += et;
                    mt.erase(mt.find(et));
                }
            }
        }
        cnt++;
    }
    reverse(all(ans2));
    cout << ans1 + ans2 << endl;
    return;
}
int main()
{

    speed;
    ll kk;
    kk = 1;
    // cin >> kk;
    while (kk--)
    {
        solve();
    }
}