content: 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();}
  
  
  	}
  }