#include <bits/stdc++.h>
using namespace std;
const int maxn = 25;
const int maxm = 55;
int n, m;
char s[maxn][maxm], t[maxn][maxm];
bool imp[maxm][maxm];

int match[maxm], mr[maxm];
bool vis[maxm];

bool check(int u) {
    for (int i = 1; i <= m; ++i) {
        if (imp[u][i]) continue;
        if (!vis[i]) {
            vis[i] = true;
            if (match[i] == -1 || check(match[i])) {
                match[i] = u;
                mr[u] = i;
                return true;
            }
        }
    }
    return false;
}

int main() {
    int T;
    for (scanf("%d", &T); T--; ) {
        memset(imp, 0, sizeof imp);
        scanf("%d%d", &n, &m);
        for (int i = 1; i <= n; ++i) {
            scanf("%s%s", s[i] + 1, t[i] + 1);
            for (int j = 1; j <= m; ++j) for (int k = 1; k <= m; ++k) {
                if (s[i][j] != t[i][k]) imp[j][k] = true;
            }
        }
        int ans = 0;
        memset(match, -1, sizeof match);
        for (int i = m; i >= 1; --i) {
            memset(vis, 0, sizeof vis);
            if (check(i)) ++ans;
        }
        if (ans < m) puts("-1");
        else {
            for (int i = 1; i <= m; ++i) {
                printf("%d%c", mr[i], " \n"[i == m]);
            }
        }
    }
    return 0;
}