#include <bits/stdc++.h>
#define ll long long
#define maxn 55 /*rem*/
#define mod 998244353
#define db double
#define vi vector<int>
#define pb push_back
using namespace std;
ll ksm(ll a, ll b) {
   if (!b) return 1;
   ll ns = ksm(a, b >> 1);
   ns = ns * ns % mod;
   if (b & 1) ns = ns * a % mod;
   return ns;
}
int fl[maxn][maxn], nr[maxn];
int p[maxn]; 
char inp[2][maxn];
int main() {
    int t;
    cin >> t;
    for (int i = 0; i < t; i++) {
        int n, m;
        cin >> n >> m;
        memset(fl, 0, sizeof(fl));
        for (int i = 0; i < n; i++) {
            scanf("%s", inp[0] + 1);
            scanf("%s", inp[1] + 1);
            for (int j = 1; j <= m; j++)
                for (int k = 1; k <= m; k++)
                    if (inp[0][j] != inp[1][k])
                        fl[j][k] = 1;
        }
        memset(nr, 0, sizeof(nr));
        int nf = 1;
        for (int i = 1; i <= m; i++) {
            p[i] = 0;
            for (int j = 1; j <= m; j++) {
                if (nr[j]) continue;
                if (fl[i][j]) continue;
                p[i] = j, nr[j] = 1;
                break;
            }
            if (!p[i]) nf = 0;
        }
        if (!nf) cout << -1 << endl;
        else {
            for (int j = 1; j <= m; j++) {
                cout << p[j];
                if (j == m) cout << endl;
                else cout << ' ';
            }
        }
    }
    return 0;
}