#include <bits/stdc++.h>
using namespace std;
using LL = long long;
#define FOR(i, x, y) for (decay<decltype(y)>::type i = (x), _##i = (y); i < _##i; ++i)
#define FORD(i, x, y) for (decay<decltype(x)>::type i = (x), _##i = (y); i > _##i; --i)
#ifdef zerol
#define dbg(x...) do { cerr << "\033[32;1m" << #x << " -> "; err(x); } while (0)
#else
#define dbg(...)
#endif // zerol
void err() { cerr << "\033[39;0m" << endl; }
template<typename T, typename... A>
void err(T a, A... x) { cerr << a << ' '; err(x...); }
// ----------------------------------------------------------------------------------------

const int N = 25, M = 55;

int tr[M][M], vis[M], ans[M];

char s[M], t[M];

int main() {
    int T; scanf("%d", &T);
    while(T--) {
        int n, m; scanf("%d%d", &n, &m);
        FOR(i, 0, m) FOR(j, 0, m) tr[i][j] = 1;
        FOR(i, 0, m) vis[i] = 0;
        FOR(i, 0, n) {
            scanf("%s%s", s, t);
            FOR(j, 0, m)
            FOR(k, 0, m) if(s[j] != t[k]) tr[j][k] = 0;
        }
        bool ok = true;
        FOR(i, 0, m) {
            bool found = false;
            FOR(j, 0, m) if(!vis[j] && tr[i][j]) {
                vis[j] = 1;
                ans[i] = j;
                found = true;
                break;
            }
            if(!found) {
                ok = false;
                break;
            }
        }
        if(ok) {
            FOR(i, 0, m) printf("%d%c", ans[i]+1, i+1==m?'\n':' ');
        } else puts("-1");
    }
    return 0;
}