#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <string>
#include <algorithm>
#include <iostream>
using namespace std;
#define ll long long

const double eps=1e-8;
const ll inf=1e9;
const ll mod=1e9+7;
const int maxn=1e5+10;

int f[60][60],g[60][60],v[60],cond,m;
char a[60],b[60],rest[60];
bool z[60][60],vis[60];

void dfs(int i)
{
    if (i==m)
    {
        cond=1;
        return;
    }
    bool c;
    int j,k,l;
    for (j=1;j<=f[i][0];j++)
        if (!cond && !vis[f[i][j]])
        {
            c=0;
            l=f[i][j];
            vis[l]=1;
            for (k=1;k<=g[l][0];k++)
            {
                rest[g[l][k]]--;
                if (g[l][k]>i && rest[g[l][k]]==0)
                    c=1;
            }

            if (!c)
            {
                v[i]=l;
                dfs(i+1);
            }
            vis[l]=0;
            for (k=1;k<=g[l][0];k++)
                rest[g[l][k]]--;
        }
}

int main()
{
    int t,i,j,k,n,wrong;
    scanf("%d",&t);
    while (t--)
    {
        memset(z,0,sizeof(z));
        scanf("%d%d",&n,&m);
        wrong=0;
        for (i=1;i<=n;i++)
        {
            scanf("%s%s",a,b);
            for (j=0;j<m;j++)
                for (k=0;k<m;k++)
                    if (a[j]!=b[k])
                        z[j][k]=1;
            sort(a,a+m);
            sort(b,b+m);
            if (strcmp(a,b)!=0)
                wrong=1;
        }
        if (wrong==1)
        {
            printf("-1\n");
            continue;
        }
        memset(f,0,sizeof(f));
        memset(g,0,sizeof(g));
        memset(rest,0,sizeof(rest));
        for (i=0;i<m;i++)
            for (j=0;j<m;j++)
                if (z[i][j]==0)
                {
                    f[i][++f[i][0]]=j;
                    rest[i]++;
                    g[j][++g[i][0]]=i;
                }

        memset(vis,0,sizeof(vis));
        cond=0;
        dfs(0);
        if (!cond)
            printf("-1");
        else
        {
            for (i=0;i<m;i++)
                printf("%d%c",v[i]+1,i==m-1?'\n':' ');
        }
    }
    return 0;
}