#include <bits/stdc++.h>
#define INF 2000000000
using namespace std;
typedef long long ll;
int read(){
    int f = 1, x = 0;
    char c = getchar();
    while(c < '0' || c > '9'){if(c == '-') f = -f; c = getchar();}
    while(c >= '0' && c <= '9')x = x * 10 + c - '0', c = getchar();
    return f * x; 
}
int n, m;
char a[55], b[55];
int cnt[55][55];
int edge[55][55];
bool vis[55];
int match[55];
int aans[55];
void init(){
    n = read(), m = read();
    memset(cnt, 0, sizeof(cnt));
    memset(edge, 0, sizeof(edge));
    for (int i = 0; i < n; ++i){
        scanf("%s%s", a, b);
        for (int j = 0; j < m; ++j){
            for (int k = 0; k < m; ++k)
                if (a[j] == b[k])
                    ++cnt[j][k];
        }
    }
    for (int i = 0; i < m; ++i)
        for (int j = 0; j < m; ++j)
            if (cnt[i][j] == n)
                edge[i][j] = 1;
}
int Edmond(int S){
    for(int i = 0; i < m; ++i){
        if(edge[S][i] && !vis[i]){
            vis[i] = 1;
            if(match[i] < 0 || Edmond(match[i])){
                match[i] = S;
                return 1;
            }
        }
    }
    return 0;
}
void solve(){
    memset(match, -1, sizeof(match));
    int ans = 0;
    for(int i=m - 1;i>= 0;--i){
        memset(vis,0,sizeof(vis));
        if(Edmond(i))ans++;
    }
    if (ans < m) printf("-1\n");
    else {
        for (int i = 0; i < m; ++i) 
            aans[match[i]] = i;
        for (int i = 0; i < m - 1; ++i)
            printf("%d ", aans[i] + 1 );
        printf("%d\n", aans[m - 1] + 1);
    }

}
int main(){
    int T = read();
    while (T--){
 init();
    solve();
    }
   
    return 0;
}