#include <cstdio>
#include <cstring>
int read()
{
    int x=0,flag=1;char c;
    while((c=getchar())<'0' || c>'9') if(c=='-') flag=-1;
    while(c>='0' && c<='9') x=(x<<3)+(x<<1)+(c^48),c=getchar();
    return x*flag;
}

int T,n,m,ans[55],used[55],mp[2505];
char a[55],b[55];

int main()
{
    T = read();
    while(T--)
    {
        memset(mp,0,sizeof (mp));
        memset(ans,0,sizeof (ans));
        memset(used,0,sizeof (used));
        n = read();m = read();
        for(int t = 1;t <= n;t ++)
        {
            scanf("%s %s",a,b);
            for(int i = 0;i < m;i ++)
                for(int j = 0;j < m;j ++)
                    if(a[i] == b[j])
                        mp[i * m + j]++;
        }
        for(int i = 0;i < m;i ++)
            for(int j = 0;j < m;j ++)
            {
                if(mp[i * m + j] == n && !ans[i] && !used[j])
                {
                    ans[i] = j + 1;
                    used[j] = 1;
                }
            }
        int flag = 0;
        for(int i = 0;i < m;i ++)
            if(!ans[i])
                flag = 1;
        if(flag) 
        {
            puts("-1");
            continue ;
        }
        for(int i = 0;i < m - 1;i ++)
            printf("%d ",ans[i]);
        printf("%d\n",ans[m - 1]);
    }
}