#include <cstdio>
#include <vector>
#include <cstring>

using namespace std;

/*struct GRAPH {
    vector<vector<int> > s;

    void ClearEdges() {
        for (auto& i : s)
            i.resize(0);
    }
    void Init(int n) {
        ClearEdges();
        s.resize(n+1);
    }
    void AddDi(int u, int v) {
        s[u].push_back(v);
    }
};*/

#define MAX1 55
#define MAX2 55
//O(VE)
int pair1[MAX1][MAX2];//pair1[0] is invalid. pair1[i][j] == k means that k(in the second group) can be distributed to i(in the first group)
int len1[MAX1];
int match2[MAX2];//match2[i] == j means that i(in the second group) is distributed to the j(in the first group)
bool vis2[MAX2];
//n1 is the size of the first group
void Init(int n1, int n2) {
    memset(len1, 0, (n1+1) * sizeof(int));
    memset(match2, 0, (n2+1) * sizeof(int));
}
void AddPair(int u, int v) {
    pair1[u][len1[u]++] = v;
}
//If succeed return 1,else return 0
bool dfs_hungary(int x) {
    for(int i = 0; i < len1[x]; i++) {
        int right = pair1[x][i];
        if(!vis2[right]) {
            vis2[right] = 1;
            if(match2[right] == 0 || dfs_hungary(match2[right])) {
                match2[right] = x;
                return 1;
            }
        }
    }
    return 0;
}
int hungary(int n1, int n2) {
    int tot = 0;
    for(int i = n1-1; i >= 0; --i) {    //If i=n1;i;--i, then the final pairs' lexicographical order will be the least
        memset(vis2, 0, (n2+1) * sizeof(bool));
        if(dfs_hungary(i))
            ++tot;
    }
    return tot;
}

#define MAXN 111

int main() {
    int T;
    static char s1[MAXN], s2[MAXN];
    static int now[MAXN];

    scanf("%d", &T);
    while (T--) {
        int m, n;

        scanf("%d%d", &m, &n);

        Init(n, n);
        scanf("%s%s", s1, s2);
        for (int i = 0; i < n; ++i) {
            for (int j = 0; j < n; ++j) {
                if (s1[i] == s2[j]) {
                    AddPair(i, j);
                }
            }
        }
        for (int i = 1; i < m; ++i) {
            scanf("%s%s", s1, s2);
            for (int i = 0; i < n; ++i) {
                int nowl = 0;
                for (int k = 0; k < len1[i]; ++k) {
                    int& j = pair1[i][k];
                    if (s2[j] == s1[i]) {
                        now[nowl++] = j;
                    }
                }
                memcpy(pair1[i], now, nowl * sizeof(int));
                len1[i] = nowl;
            }
        }
        int ans = hungary(n, n);
        if (ans < n) {
            puts("-1");
        } else {
            for (int i = 0; i < n; ++i) {
                now[match2[i]] = i;
            }
            for (int i = 0; i < n; ++i) {
                printf("%d%c", now[i] + 1, i == n-1 ? '\n' : ' ');
            }
        }
    }
    return 0;
}