#include<bits/stdc++.h>
using namespace std;

#define pb push_back
#define mp make_pair
#define ALL(x) (x).begin(),(x).end()
typedef long long ll;
typedef pair<int,int> pii;
const int maxn = 3e5 + 70;
const int INF = 0x3f3f3f3f;
const ll inf = 0x3f3f3f3f3f3f3f3f;
const int MOD = 1e9 + 7;
const double eps = 1e-7;
const double PI = acos(-1.0);

int n, m, k;

char s[21][51], t[21][51];

int p[51];

bool solve(int d, vector<int>& a, vector<int>& b){
    if(d==n+1){
        for(int i=0;i<a.size();i++){
            p[a[i]]=b[i];
        }
        return true;
    }
    else{
        vector<int> a2[26], b2[26];
        for(int i=0;i<a.size();i++){
            int x=a[i], y=b[i];
            a2[s[d][x]-'a'].pb(x);
            b2[t[d][y]-'a'].pb(y);
        }

        for(int i=0;i<26;i++){
            if(a2[i].size()!=b2[i].size()) return false;
            if(a2[i].size()){
                if(!solve(d+1,a2[i],b2[i])) return false;
            }
        }
    }
    return true;
}

int main(){
    //freopen("in.txt", "r", stdin);
    int T;
    cin>>T;
    while(T--){
        scanf("%d %d",&n,&m);
        for(int i=1;i<=n;i++){
            scanf("%s",s[i]+1);
            scanf("%s",t[i]+1);
        }

        vector<int> a(m), b(m);
        for(int i=0;i<m;i++) a[i]=b[i]=i+1;

        if(solve(1,a,b)){
            for(int i=1;i<=m;i++){
                if(i>1) putchar(' ');
                printf("%d",p[i]);
            }
            printf("\n");
        }
        else printf("-1\n");
    }
    return 0;
}