#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>
using namespace std;

const int maxn = 110;
struct BPM {
  vector<int> g[maxn];
  int n, m, l[maxn];
  bool vis[maxn];
  void init() {
    for (int i = 0; i < maxn; ++i) g[i].clear();
  }
  bool match(int x) {
    for (int y : g[x])
      if (!vis[y]) {
        vis[y] = true;
        if (l[y] == -1 || match(l[y])) {
          l[y] = x;
          return true;
        }
      }
    return false;
  }
  int solve() {
    memset(l, -1, sizeof l);
    int ans = 0;
    for (int i = n - 1; i >= 0; --i) {
      memset(vis, 0, sizeof vis);
      if (match(i))
        ans++;
    }
    return ans;
  }
} s;

void solve() {
  int n, m;
  cin >> n >> m;
  static bool g[111][111];
  for (int i = 0; i < m; ++i) {
    for (int j = 0; j < m; ++j) {
      g[i][j] = true;
    }
  }
  bool gg = false;
  for (int i = 0; i < n; ++i) {
    string a, b;
    cin >> a >> b;
    for (int i = 0; i < m; ++i) {
      for (int j = 0; j < m; ++j) {
        if (a[i] != b[j]) {
          g[i][j] = false;
        }
      }
    }
    sort(a.begin(), a.end());
    sort(b.begin(), b.end());
    if (a != b) gg = true;
  }
  if (gg) {
    cout << -1 << endl;
    return;
  }
  s.init();
  s.n = m * 2;
  for (int i = 0; i < m; ++i) {
    for (int j = 0; j < m; ++j) {
      if (g[i][j]) s.g[i].push_back(j + m);
    }
  }
  if (s.solve() != m) {
    cout << -1 << endl;
  } else {
    vector<int> ans(m);
    for (int i = 0; i < m; ++i) {
      ans[s.l[i + m]] = i + 1;
    }
    for (int i = 0; i < m; ++i) {
      cout << ans[i] << (i == m - 1 ? '\n' : ' ');
    }
  }
}

int main() {
  ios::sync_with_stdio(false);
  int T;
  cin >> T;
  while (T-- > 0) {
    solve();
  }
  return 0;
}