#include<iostream>
#include<algorithm>
#include<cstring>
#include<cstdio>
#include<cmath>
#include<queue>
#include<map>
#include<cstdlib>
#include<string>
#include<functional>
#include<list>
#include<stack>
using namespace std;
string a[22], b[22];
int p[55];
int cnt;
int vis[55];
int main()
{
    //freopen("in.txt", "r", stdin);
    int t;
    cin >> t;
    while (t--)
    {
        memset(vis, 0, sizeof(vis));
        cnt = 0;
        int n, m;
        cin >> n >> m;
        for (int i = 1;i <= n;i++)
            cin >> a[i] >> b[i];
        int i, j, k;
        for (i = 0;i < m;i++)
            for (j = 0;j < m;j++) {
                for (k = 1;k <= n;k++)
                    if (a[k][i] != b[k][j])break;
                if (k == n + 1 && !vis[j + 1]) { p[cnt++] = j + 1;vis[j + 1] = 1;break; }
            }
        if (cnt < m) {
            cout << -1 << endl;continue;
        }
        for (int i = 0;i < m;i++) {
            if (i == cnt - 1) {
                cout << p[i] << endl;
                break;
            }
            cout << p[i] << " ";
        }
    }
    return 0;
}