#include <bits/stdc++.h>
using namespace std;

const int inf = 0x3f3f3f3f;

int T, n, m, link[55];
bool g[55][55], nvis[55], del[55];
char s[55], t[55];

bool dfs(int u)
{
    for (int v = 1; v <= m; ++v)
    {
        if (!g[u][v] || !nvis[v] || del[v])
            continue;
        nvis[v] = false;
        if (!link[v] || dfs(link[v]))
        {
            link[v] = u;
            return true;
        }
    }
    return false;
}
int solve(int bg)
{
    int ret = 0;
    for (int i = 1; i <= m; ++i)
        link[i] = 0;
    for (int i = bg; i <= m; ++i)
    {
        for (int j = 1; j <= m; ++j)
            nvis[j] = true;
        if (dfs(i))
            ++ret;
    }
    return ret;
}

int main()
{
    scanf("%d", &T);
    while (T--)
    {
        scanf("%d%d", &n, &m);
        for (int i = 1; i <= m; ++i)
            for (int j = 1; j <= m; ++j)
                g[i][j] = true;
        for (int i = 1; i <= n; ++i)
        {
            scanf("%s%s", s + 1, t + 1);
            for (int i = 1; i <= m; ++i)
                for (int j = 1; j <= m; ++j)
                    if (t[j] != s[i])
                        g[i][j] = false;
        }
        for (int i = 1; i <= m; ++i)
            del[i] = false;
        if (solve(1) != m)
        {
            puts("-1");
            continue;
        }
        for (int i = 1; i <= m; ++i)
            for (int j = 1; j <= m; ++j)
                if (g[i][j] && !del[j])
                {
                    del[j] = true;
                    if (solve(i + 1) == m - i)
                    {
                        printf("%d%c", j, " \n"[i == m]);
                        break;
                    }
                    del[j] = false;
                }
    }
    return 0;
}