#include<iostream>
#include<algorithm>
#include<vector>
#include<queue>
#include<numeric>
using namespace std;
int a[60][60];
int ans[60];
int n, m;
char s1[60],s2[60];
int vis[60];
vector<int> vec[60];

int dfs(int x,int y) {
    vis[y] = 1;
    if (x == m)return 1;
    for (int i = 0; i < vec[x+1].size(); i++) {
        if (vis[vec[x+1][i]])continue;
        ans[x+1] = vec[x+1][i];
        if (dfs(x + 1,ans[x+1]))return 1;
    }
    vis[y] = 0;
    return 0;
}

int main() {
    int t; cin >> t;
    while (t--) {
        cin >> n >> m;
        for (int i = 1; i <= m; i++) {
            for (int j = 1; j <= m; j++) {
                a[i][j] = 1;
            }
            vis[i] = 0;
            vec[i].clear();
        }
        for (int k = 1; k <= n; k++) {
            cin >> s1 + 1 >> s2 + 1;
            for (int i = 1; i <= m; i++) {
                for (int j = 1; j <= m; j++) {
                    if (s1[i] != s2[j])a[i][j] = 0;
                }
            }
        }
        for (int i = 1; i <= m; i++) {
            for (int j = 1; j <= m; j++) {
                if (a[i][j])vec[i].push_back(j);
            }
        }

        int flg1 = 1;
        for (int i = 1; i <= m; i++) {
            int flg = 1;
            for (int j = 1; j <= m; j++) {
                if (a[i][j] == 1) {
                    flg = 0;
                    break;
                }
            }
            if (flg)flg1 = 0;
        }
        for (int i = 1; i <= m; i++) {
            int flg = 1;
            for (int j = 1; j <= m; j++) {
                if (a[j][i] == 1) {
                    flg = 0;
                    break;
                }
            }
            if (flg)flg1 = 0;
        }
        if (flg1 == 0) {
            cout << -1 << endl;
            continue;
        }
        if(flg1)for (int i = 1; i <= m; i++) {
            if (a[1][i] == 1) {
                ans[1] = i;
                if (dfs(1,i)) {
                    flg1 = 0;
                    break;
                }
            }
        }
        if (!flg1) {
            for (int i = 1; i < m; i++)cout << ans[i] << " "; cout << ans[m] << endl;
        }
        else cout << -1 << endl;
    }
}