#include<bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define SZ(x) ((int)x.size())
#define L(i,u) for (register int i=head[u]; i; i=nxt[i])
#define rep(i,a,b) for (register int i=(a); i<=(b); i++)
#define per(i,a,b) for (register int i=(a); i>=(b); i--)
using namespace std;
typedef long long ll;
typedef unsigned int ui;
typedef pair<int,int> Pii;
typedef vector<int> Vi;
template<class T> inline void read(T &x){
    x=0; char c=getchar(); int f=1;
    while (!isdigit(c)) {if (c=='-') f=-1; c=getchar();}
    while (isdigit(c)) {x=x*10+c-'0'; c=getchar();} x*=f;
}
template<class T> inline void umin(T &x, T y){x=x<y?x:y;}
template<class T> inline void umax(T &x, T y){x=x>y?x:y;}
inline ui R() {
    static ui seed=416;
    return seed^=seed>>5,seed^=seed<<17,seed^=seed>>13;
}
const int N = 233;
int n,m,cnt[55][55];bool vis[55];
void solve(){
    memset(vis,0,sizeof(vis));static int ans[55];
    rep(i,1,m){
        bool ok=0;
        rep(j,1,m)if(!vis[j]&&cnt[i][j]==n){
            vis[j]=1;ok=1;ans[i]=j;break;
        }
        if(!ok){puts("-1");return;}
    }
    rep(i,1,m){printf("%d",ans[i]);if(i+1<=m)putchar(' ');}
    puts("");
}
int main() {
    int T;read(T);
    while(T--){
        read(n);read(m);
        memset(cnt,0,sizeof(cnt));
        rep(t,1,n){
            static char a[55],b[55];
            scanf("%s%s",a+1,b+1);
            rep(i,1,m)rep(j,1,m)cnt[i][j]+=a[i]==b[j];
        }
        solve();
    }
    return 0;
}