#include <cstdio>
#include <algorithm>
#include <cstring>
using namespace std;
int cas,n,m,a[110][110],match[110],vis[110],Ans[110];
char s1[110],s2[110];
int dfs(int u){
    vis[u]=1;
    for (int i=1;i<=m;i++)
        if (!a[u][i]){
            if (!match[i]||!vis[match[i]]&&dfs(match[i])){
                match[i]=u;
                return 1;
            }
        }
    return 0;
}
int main(){
    scanf("%d",&cas);
    while (cas--){
        memset(a,0,sizeof a);
        memset(match,0,sizeof match);
        scanf("%d%d",&n,&m);
        for (int i=1;i<=n;i++){
            scanf("%s%s",s1,s2);
            for (int j=0;j<m;j++)
                for (int k=0;k<m;k++)
                    if (s1[j]!=s2[k])a[j+1][k+1]=1;
        }
        int ans=0;
        for (int i=m;i;i--){
            memset(vis,0,sizeof vis);
            if (!dfs(i)){ans=1;break;}
        }
        //for (int i=1;i<=m;i++)printf("%d ",match[i]);puts("");
        if (ans)puts("-1");
            else{
                for (int i=1;i<=m;i++)Ans[match[i]]=i;
                for (int i=1;i<m;i++)printf("%d ",Ans[i]);printf("%d\n",Ans[m]);
            }
    }
}