#include <bits/stdc++.h>

#define el '\n'
#define Beevo ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

typedef long long ll;
typedef long double ld;

using namespace std;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

void testCase() {
    string s, t;
    cin >> s >> t;

    s += t;

    sort(s.begin(), s.end());

    cout << s;
}

signed main() {
    Beevo

    int t = 1;
//    cin >> t;

    while (t--)
        testCase();
}