import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.StreamTokenizer;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

public class Main{
    private static boolean isMatch(int k,int j) {
        int match = 0;
        for (int i = 0; i < n; i++) {
        if(s[2*i].charAt(k)!=s[2*i+1].charAt(j))
        {
            return false;
        }
        }
    return true;

    }
    
    private static int n, m;
    private static int[] p = new int[60], vis = new int[60];
    private static String[] s = new String[50];
    private static boolean flag = false;
    private static void DFS(int i) {
        if (i == m) {
            flag = true;
            return;
        }
        for (int j = 0; j < m; j++) {
            if (vis[j] == 0&&!flag) {
                vis[j] = 1;
                if(isMatch(i, j))
                {
                    p[i] = j;
                    DFS(i + 1);
                }
                vis[j] = 0;
            }
        }
    }

    private static boolean preMatch()
    {
        Map<Character,Integer> counts =new HashMap<Character,Integer>();
        for(int i=0;i<26;i++)
        {
            counts.put((char) ('a'+i), 0);
        }
        for(int i=0;i<n;i++)
        {
            for(int j=0;j<s[2*i].length();j++)
            {
                counts.put(s[2*i].charAt(j), counts.get(s[2*i].charAt(j))+1);
            }
            for(int j=0;j<s[2*i+1].length();j++)
            {
                counts.put(s[2*i+1].charAt(j), counts.get(s[2*i+1].charAt(j))-1);                
            }
            for(Map.Entry<Character,Integer> c:counts.entrySet())
            {
                if(c.getValue()!=0)
                {
                    return false;
                }
            }
            
        }
        return true;
    }


    public static void main(String[] args) throws IOException {
        StreamTokenizer st = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
        PrintWriter pr = new PrintWriter(System.out);
        int K;
        st.nextToken();
        K = (int) st.nval;
        while (K-- > 0) {
            flag = false;
            Arrays.fill(vis, 0);
            st.nextToken();
            
            n = (int) st.nval;
            st.nextToken();
            m = (int) st.nval;
            for (int i = 0; i < 2 * n; i++) {
                st.nextToken();
                s[i] = st.sval;
            }
            if(preMatch())
            {
            DFS(0);
            }
            if (flag) {
                for (int i = 0; i < m; i++) {
                    pr.print(p[i]+1);
                    if (i != m - 1) {
                        pr.print(" ");
                    }
                }
                pr.println();
            } else {
                pr.println(-1);
            }
            pr.flush();
        }
    }
}