//12252024832524
#include <cstdio>
#include <cstring>
#include <algorithm>
#define Min(x,y) (x<y?x:y)
#define Max(x,y) (x>y?x:y)
using namespace std;

typedef long long LL;
const int MAXN = 55;
int n,m;
int vis[MAXN],ans[MAXN];
bool vis1[MAXN][MAXN],vis2[MAXN][MAXN];
bool used[MAXN];
char a[MAXN],b[MAXN];

int Read()
{
    int x1 = 0,f1 = 1;char c1 = getchar();
    while(c1 > '9' || c1 < '0'){if(c1 == '-')f1 = -1;c1 = getchar();}
    while(c1 >= '0' && c1 <= '9'){x1 = (x1*10) + (c1^48);c1 = getchar();}
    return x1 * f1;
}
void Put(int x)
{
    if(x > 9)
        Put(x/10);
    putchar(x%10^48);
}
bool dfs(int x)
{
    if(!x)
        return 1;
    for(int i = m;i >= 1;-- i)
    {
        if(vis1[x][i] && !used[i])
        {
            used[i] = 1;
            if(dfs(vis[i]))
            {
                vis[i] = x;
                return 1;
            }
        }
    }
    return 0;
}

int main()
{
//    freopen(".in","r",stdin);
//    freopen(".out","w",stdout);
    for(int T = Read(); T ;-- T)
    {
        n = Read();
        m = Read();
        memset(vis,0,sizeof(vis));
        memset(vis1,0,sizeof(vis1));
        scanf("%s %s",a+1,b+1);
        for(int i = 1;i <= m;++ i)
            for(int j = 1;j <= m;++ j)
                if(a[i] == b[j])
                    vis1[i][j] = 1;
        for(int i = 2;i <= n;++ i)
        {
            scanf("%s %s",a+1,b+1);
            for(int j = 1;j <= m;++ j)
                for(int k = 1;k <= m;++ k)
                    if(a[j] == b[k])
                        vis2[j][k] = 1;
            for(int j = 1;j <= m;++ j)
                for(int k = 1;k <= m;++ k)
                    vis1[j][k] &= vis2[j][k];
            memset(vis2,0,sizeof(vis2));
        }
        for(int i = 1;i <= m;++ i)
        {
            memset(used,0,sizeof(used));
            if(!dfs(i))
            {
                puts("-1");
                break;
            }
            if(i == m)
            {
                for(int j = 1;j <= m;++ j)
                    ans[vis[j]] = j;
                for(int j = 1;j < m;++ j)
                    printf("%d ",ans[j]);
                printf("%d\n",ans[m]);
            }
        }
    }
    return 0;
}