package v006;

import java.io.BufferedReader;

import java.io.FileReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.PrintWriter;

import java.util.Arrays;

import java.util.StringTokenizer;

public class DNASorting_UVa612 {

public static void main(String[] args) throws Exception

{

Scanner sc = new Scanner(System.in);

PrintWriter out = new PrintWriter(System.out);

int tc = sc.nextInt();

while(tc-->0)

{

int n = sc.nextInt(), m = sc.nextInt();

Pair[] seq = new Pair[m];

for(int i = 0; i < m; ++i)

{

String s = sc.next();

seq[i] = new Pair(s, compute(n, s.toCharArray()), i);

}

Arrays.sort(seq);

for(int i = 0; i < m; ++i)

out.println(seq[i].s);

if(tc != 0)

out.println();

}

out.flush();

out.close();

}

static int compute(int n, char[] s)

{

int count = 0;;

for(int i = 0; i < n; ++i)

for(int j = i + 1; j < n; ++j)

if(s[i] > s[j])

++count;

return count;

}

static class Pair implements Comparable<Pair>

{

String s;

int inv, idx;

Pair(String a, int b, int c)

{

s = a;

inv = b;

idx = c;

}

public int compareTo(Pair p)

{

if(inv != p.inv)

return inv - p.inv;

return idx - p.idx;

}

}

static class Scanner

{

StringTokenizer st;

BufferedReader br;

public Scanner(InputStream s){ br = new BufferedReader(new InputStreamReader(s));}

public Scanner(FileReader r){ br = new BufferedReader(r);}

public String next() throws IOException

{

while (st == null || !st.hasMoreTokens())

st = new StringTokenizer(br.readLine());

return st.nextToken();

}

public int nextInt() throws IOException {return Integer.parseInt(next());}

public long nextLong() throws IOException {return Long.parseLong(next());}

public String nextLine() throws IOException {return br.readLine();}

public double nextDouble() throws IOException

{

String x = next();

StringBuilder sb = new StringBuilder("0");

double res = 0, f = 1;

boolean dec = false, neg = false;

int start = 0;

if(x.charAt(0) == '-')

{

neg = true;

start++;

}

for(int i = start; i < x.length(); i++)

if(x.charAt(i) == '.')

{

res = Long.parseLong(sb.toString());

sb = new StringBuilder("0");

dec = true;

}

else

{

sb.append(x.charAt(i));

if(dec)

f *= 10;

}

res += Long.parseLong(sb.toString()) / f;

return res * (neg?-1:1);

}

public boolean ready() throws IOException {return br.ready();}

}

}