#include <bits/stdc++.h>
#define pb push_back
#define F first
#define S second
#define MP make_pair
#define all(x) x.begin(),x.end()
#define Hagry ios::sync_with_stdio(false);cout.tie(NULL);cin.tie(NULL);

using namespace std;
using ll = long long;
using pi = pair<int, int>;
using vi = vector<int>;
using vpi = vector <pair<int, int>>;
using vvi = vector <vector<int>>;

const int OO = 1e9 + 5;
const int N = 2e5 + 5;

void TC(){
    string a, b;
    cin >> a >> b;
    a += b;
    sort(all (a));
    cout << a;
}

int32_t main() {
#ifndef ONLINE_JUDGE
    freopen("input.in", "r", stdin); freopen("output.out", "w", stdout);
#endif
    Hagry
    int t = 1;
//    cin >> t;
    while (t--) {
        TC();
        cout << '\n';
    }
    return 0;
}