#include <cstdio>
#include <algorithm>

namespace Dinic {
    typedef long long LL;
    const LL Inf = 0x7fffffffffffffff;
    const int MN = 105, MM = 2605;
    
    int N, S, T;
    int h[MN], iter[MN], nxt[MM * 2], to[MM * 2], tot; LL w[MM * 2];
    
    inline void Init(int _N) {
        N = _N, tot = 1;
        for (int i = 1; i <= N; ++i) h[i] = 0;
    }
    inline void SetST(int _S, int _T) { S = _S, T = _T; }
    
    inline void ins(int u, int v, LL x) { nxt[++tot] = h[u], to[tot] = v, w[tot] = x, h[u] = tot; }
    inline void insw(int u, int v, LL w1 = Inf, LL w2 = 0) {
        if (!u) u = S; if (!v) v = T;
        ins(u, v, w1), ins(v, u, w2);
    }
    
    int lv[MN], que[MN], l, r;
    
    inline bool Lvl() {
        for (int i = 1; i <= N; ++i) lv[i] = 0;
        lv[S] = 1;
        que[l = r = 1] = S;
        while (l <= r) {
            int u = que[l++];
            for (int i = h[u]; i; i = nxt[i])
                if (w[i] && !lv[to[i]]) {
                    lv[to[i]] = lv[u] + 1;
                    que[++r] = to[i];
                }
        }
        return lv[T] != 0;
    }
    
    LL Flow(int u, LL f) {
        if (u == T) return f;
        LL d = 0, s = 0;
        for (int &i = iter[u]; i; i = nxt[i])
            if (w[i] && lv[to[i]] == lv[u] + 1) {
                d = Flow(to[i], std::min(f, w[i]));
                f -= d, s += d;
                w[i] -= d, w[i ^ 1] += d;
                if (!f) break;
            }
        return s;
    }
    
    inline LL Dinic() {
        LL Ans = 0;
        while (Lvl()) {
            for (int i = 1; i <= N; ++i) iter[i] = h[i];
            Ans += Flow(S, Inf);
        }
        return Ans;
    }
}

typedef long long LL;

int main() {
    int T; scanf("%d", &T);
    while (T--) {
        int N, M;
        static char S1[55], S2[55];
        static int C[55][55], P[55], V[55];
        scanf("%d%d", &N, &M);
        for (int i = 1; i <= M; ++i) P[i] = V[i] = 0;
        for (int i = 1; i <= M; ++i)
            for (int j = 1; j <= M; ++j)
                C[i][j] = 1;
        for (int k = 1; k <= N; ++k) {
            scanf("%s%s", S1 + 1, S2 + 1);
            for (int i = 1; i <= M; ++i)
                for (int j = 1; j <= M; ++j)
                    if (S1[i] != S2[j]) C[i][j] = 0;
        }
        Dinic::Init(2 * M + 2), Dinic::SetST(2 * M + 1, 2 * M + 2);
        for (int i = 1; i <= M; ++i) Dinic::insw(0, i, 1), Dinic::insw(M + i, 0, 1);
        for (int i = 1; i <= M; ++i)
            for (int j = 1; j <= M; ++j)
                if (C[i][j]) Dinic::insw(i, M + j);
        if (Dinic::Dinic() != M) { puts("-1"); continue; }
        for (int k = 1; k <= M; ++k) {
            int ch = 0;
            for (int c = 1; c <= M; ++c) {
                if (V[c]) continue;
                Dinic::Init(2 * M + 2), Dinic::SetST(2 * M + 1, 2 * M + 2);
                for (int i = 1; i <= M; ++i) Dinic::insw(0, i, 1), Dinic::insw(M + i, 0, 1);
                for (int i = k + 1; i <= M; ++i)
                    for (int j = 1; j <= M; ++j)
                        if (!V[j] && j != c && C[i][j]) Dinic::insw(i, M + j);
                if (Dinic::Dinic() == M - k) { ch = c; break; }
            }
            if (!ch) { puts("??"); return 0x55; }
            P[k] = ch, V[ch] = 1;
        }
        for (int i = 1; i <= M; ++i) printf("%d%c", P[i], " \n"[i == M]);
    }
    return 0;
}