#include <bits/stdc++.h>
using namespace std;
int t, p[123], vis[123], n, m;
char a[123][123], b[123][123];

bool chk() {
    for (int i = 1; i <= n; ++i)
        for (int j = 1; j <= m; ++j)
            if (p[j] && a[i][j] != b[i][p[j]]) return 0;
    return 1;
}

int main() {
    scanf("%d", &t);
    while (t--) {
        scanf("%d%d", &n, &m);
        for (int i = 1; i <= n; ++i) {
            scanf("%s%s", a[i] + 1, b[i] + 1);
        }
        for (int i = 1; i <= m; ++i) vis[i] = p[i] = 0;
        bool fd = 1;
        for (int i = 1; i <= m; ++i) {
            for (int j = 1; j <= m; ++j)
                if (!vis[j]) {
                    p[i] = j;
                    if (chk()) {
                        vis[j] = 1; break;
                    }
                    p[i] = 0;
                }
            if (!p[i]) {
                fd = 0; break;
            }
        }
        if (!fd) printf("-1\n");
        else {
            for (int i = 1; i <= m; ++i) printf("%d%c", p[i], " \n"[i == m]);
        }
    }
}