#include <fstream>
#include <cstring>
#include <vector>

using namespace std;

ifstream fin ("fbsearch.in");
ofstream fout ("fbsearch.out");

class Trie
{
    public :
        int val, val_max, id, id_max;
        Trie *son[ 27 ];

        Trie()
        {
            val = val_max = id = id_max = 0;
            memset(son, 0, sizeof(son));
        }
};

int t, n, m, now_id;
Trie *T = new Trie;
char C[36], V[100010][36];


void Ins(Trie *nod, char *c)
{
    if (*c == '\0')
    {
        nod->id = now_id;
        now->val = 0;
        return;
    }

    if (nod->son[CH(*c)] == '\0')
    {
        nod->son[CH(*c)] = new Trie;
    }

}

int main()
{
    fin >> t;
    while (t --)
    {
        memset(V, '\0', sizeof(V));

        fin >> n >> m;
        for (int i = 1; i <= n; i ++)
        {
            fin.getline(V[i], 32);
            now_id = i;
            Ins(T, V[i]);
        }
    }
}