#include <cstdio>
#include <cstdlib>
#include <cstring>

using namespace std;

char in[30][60], out[30][60];
int T, N, M, ans[60], cnt[30];
bool used[60], flag;

bool dfs(int x) {
    if (x > M)
        return 1;
    for (int i = 1; i <= M; ++i)
        if (!used[i]) {
            bool flag = 1;
            for (int j = 1; j <= N; ++j)
                if (in[j][x] != out[j][i]) {
                    flag = 0;
                    break;
                }
            if (flag) {
                used[i] = 1;
                ans[x] = i;
                if (dfs(x + 1)) {
                    used[i] = 0;
                    return 1;
                }
                used[i] = 0;
            }
        }
    return 0;
}

int main() {
    scanf("%d", &T);
    while (T--) {
        scanf("%d%d", &N, &M);
        flag = 1;
        for (int i = 1; i <= N; ++i) {
            scanf("%s%s", in[i] + 1, out[i] + 1);
            memset(cnt, 0, sizeof(cnt));
            for (int j = 1; j <= M; ++j) {
                ++cnt[in[i][j] - 'a'];
                --cnt[out[i][j] - 'a'];
            }
            for (int j = 0; j < 26; ++j)
                if (cnt[j] != 0) {
                    flag = 0;
                    break;
                }
        }
        if (flag && dfs(1)) {
            printf("%d", ans[1]);
            for (int i = 2; i <= M; ++i)
                printf(" %d", ans[i]);
            printf("\n");
        } else
            printf("-1\n");
    }
    return 0;
}