#include <iostream>
#include <string>

using namespace std;

string ldk(string &kld, string &lkd)
{
    if (kld.empty()) return "";

    char koren = kld[0];

    int index = lkd.find(koren);

    string kld_l = kld.substr(1, index);
    string kld_d = kld.substr(index + 1);

    string lkd_l = lkd.substr(0, index);
    string lkd_d = lkd.substr(index + 1);

    return ldk(kld_l, lkd_l)
         + ldk(kld_d, lkd_d)
         + koren;
}

int main(void)
{
    string kld, lkd;
    cin >> kld >> lkd;

    cout << ldk(kld, lkd) << endl;
    
    return 0;
}