#include <algorithm>

#include <iostream>

#include <string>

#include <stdio.h>

#include <memory.h>

namespace cc

{

using std::cin;

using std::cout;

using std::endl;

using std::move;

using std::sort;

using std::string;

int cmp(const string &a, const string &b)

{

    return a.length() < b.length();

}

const int N = ;

void solve()

{

    int n;

    cin >> n;

    getchar();

    getchar();

    int tt = ;

    while (n--)

    {

        if (tt != )

            cout << endl;

        ++tt;

        string strs[N];

        int total = ;

        string s;

        int totalLength = ;

        while (getline(cin, s))

        {

            if (s.length() == )

                break;

            strs[total++] = s;

        }

        sort(strs, strs + total, cmp);

        totalLength = strs[].size() + strs[total - ].size();

        int vis[N];

        for (int i = ;; i++)

        {

            memset(vis, , sizeof(vis));

            string temp = strs[i] + strs[total - ];

            int count = ;

            //vis[i] = vis[total - 1] = 1;

            for (int j = ; j < total; j++)

            {

                for (int k = ; k < total; k++)

                {

                    if (vis[j] || vis[k] || k == j || strs[j].length() + strs[k].length() != totalLength)

                        continue;

                    if (strs[k] + strs[j] == temp || strs[j] + strs[k] == temp)

                    {

                        vis[j] = vis[k] = ;

                        ++count;

                        break;

                    }

                }

            }

            if (count == total / )

            {

                cout << temp << endl;

                break;

            }

            else

            {

                memset(vis, , sizeof(vis));

                string temp = strs[total - ] + strs[i];

                count = ;

                for (int j = ; j < total; j++)

                {

                    for (int k = ; k < total; k++)

                    {

                        if (vis[j] || vis[k] || k == j || strs[j].length() + strs[k].length() != totalLength)

                            continue;

                        if (strs[k] + strs[j] == temp || strs[j] + strs[k] == temp)

                        {

                            vis[j] = vis[k] = ;

                            ++count;

                            break;

                        }

                    }

                }

                if (count == total / )

                {

                    cout << temp << endl;

                    break;

                }

            }

        }

    }

}

} // namespace cc

int main()

{

#ifndef ONLINE_JUDGE

    freopen("/Users/caicai/in", "r", stdin);

#endif // !ONLINE_JUDGE

    cc::solve();

#ifndef ONLINE_JUDGE

    while (true)

        ;

#endif // !ONLINE_JUDGE

    return ;

}