#include <bits/stdc++.h>
using namespace std;
int T, n, m, ans[55];
bool to[55][55], chk[55], flag;
char st[55], ed[55];
int main()
{
  scanf("%d", &T);
  while (T--)
  {
    scanf("%d%d", &n, &m);
    memset(to, true, sizeof to);
    for (int i = 1; i <= n; i++)
    {
      scanf("%s", st + 1);
      scanf("%s", ed + 1);
      for (int j = 1; j <= m; j++)
        for (int k = 1; k <= m; k++)
          if (st[j] != ed[k])
            to[j][k] = false;
    }
    memset(chk, false, sizeof chk);
    memset(ans, 0, sizeof ans);
    for (int i = 1; i <= m; i++)
      for (int j = 1; j <= m; j++)
        if (to[i][j] && !chk[j])
        {
          chk[j] = true;
          ans[i] = j;
          break;
        }
    flag = true;
    for (int i = 1; i <= m; i++)
      if (ans[i] == 0)
      {
        flag = false;
        break;
      }
    if (!flag) puts("-1");
    else
      for (int i = 1; i <= m; i++)
        printf("%d%c", ans[i], i == m? '\n' : ' ');
  }
}