/*
#include <cstdio>

using namespace std;
const int maxn = 60;
int n , m;
int ans[maxn];

char in[22][maxn] , out[22][maxn];
vector<int> p[30];
bool flag;

struct node
{
    char in[maxn] , out[maxn];
    int mx;
    bool can;

    void init()
    {
        int a[30] , b[30];
        scanf("%s%s",in,out);
        for( int i = 0; i < 26; i++ ) a[i] = b[i] = 0;
        for( int i = 0; i < m; i++ ){
            a[ in[i]-'a' ]++ , b[ out[i]-'a' ]++;
        }
        mx = 0 , can = true;
        for( int i = 0; i < 26; i++ )
        {
            mx = max(mx,a[i]);
            if ( a[i] != b[i] ){
                can = false;
                break;
            }
        }
    }
    bool operator<(const node& rhs) const
    {
        return mx < rhs.mx;
    }
}x[30];

void dfs( int now )
{
    if ( flag ) return;
    if ( now >= m )
    {
        return
    }
}

int solve()
{
    for( int i = 1; i <= n; i++ )
        if ( !x[i].can ) return -1;
    sort(x+1,x+1+n);
    for( int i = 0; i < 26; i++ ) p[i].clear();
    for( int i = 0; i < m; i++ ) p[ x[1].out[i]-'a' ].push_back(i);    
    flag = false;
    dfs( 1 );
}

int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d%d",&n,&m);
        for( int i = 1; i <= n; i++ ) x[i].init();
        printf("%d\n",solve() );
    }
    return 0;
}*/

#include <cmath>
#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

bool a[50][50];

int main()
{
    int T;
    scanf("%d", &T);
    while (T--) {
        int N, M;
        char in[60], out[60];
        scanf("%d%d", &N, &M);
        memset(a, 0, sizeof(a));
        for (int k = 0; k < N; k++) {
            scanf("%s%s", in, out);
            for (int i = 0; i < M; i++) {
                for (int j = 0; j < M; j++) {
                    if (in[i] != out[j]) {
                        a[i][j] = 1;
                    }
                }
            }
        }
        int ret[50];
        bool flag = 0;
        for (int i = 0; i < M; i++) {
            int j = 0;
            for (j = 0; j < M; j++) {
                if (a[i][j] == 0) {
                    ret[i] = j;
                    for (int k = i+1; k < M; k++) {
                        a[k][j] = 1;
                    }
                    break;
                }
            }
            if (j == M) flag = 1;
        }
        if (flag) {
            printf("-1\n");
        } else {
            //puts("ans");
            for (int i = 0; i < M-1; i++) {
                printf("%d ", ret[i]+1);
            }
            printf("%d\n", ret[M-1]+1);
        }
    }
    return 0;
}