content: package v004;
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.Comparator;
  import java.util.StringTokenizer;
  import java.util.TreeSet;
  
  
  public class BoggleBlitz_UVa487 {
  
  	static int[] dx = new int[] {0, 0, -1, 1, -1, -1, 1, 1};
  	static int[] dy = new int[] {-1, 1, 0, 0, 1, -1, -1, 1};
  	static char[][] grid;
  	static TreeSet<String> ans;
  	static int N;
  	static boolean[][] visited;
  	
  	static boolean valid(int x, int y)
  	{
  		return x != -1 && y != -1 && x != N && y != N && !visited[x][y]; 
  	}
  	
  	static void dfs(int x, int y, String s)
  	{
  		char c = grid[x][y];
  		s += c;
  		if(s.length() >= 3)
  		ans.add(s);
  		visited[x][y] = true;
  		for(int k = 0; k < 8; ++k)
  		{
  			int i = x + dx[k], j = y + dy[k];
  			if(valid(i, j) && c < grid[i][j])
  				dfs(i, j, s);
  		}
  		visited[x][y] = false;
  	}
  	
  	public static void main(String[] args) throws IOException 
  	{
  		Scanner sc = new Scanner(System.in);
  		PrintWriter out = new PrintWriter(System.out);
  		StringBuilder sb = new StringBuilder();
  		
  		int tc = sc.nextInt();
  		while(tc-->0)
  		{
  			N = sc.nextInt();
  			grid = new char[N][N];
  			for(int i = 0; i < N; ++i)
  				grid[i] = sc.next().toCharArray();
  			visited = new boolean[N][N];
  			ans = new TreeSet<String>(new Sorter());
  			for(int i = 0; i < N; ++i)
  				for(int j = 0; j < N; ++j)
  					dfs(i, j, "");
  			for(String s: ans)
  				sb.append(s + "\n");
  			if(tc != 0)
  				sb.append("\n");
  		}
  		out.print(sb);
  		out.flush();
  		out.close();
  	}
  	
  	static class Sorter implements Comparator<String>
  	{
  
  		public int compare(String o1, String o2) 
  		{
  			if(o1.length() != o2.length())
  				return o1.length() - o2.length();
  			return o1.compareTo(o2);
  		}
  		
  	}
  
  	static class Scanner 
  	{
  		StringTokenizer st;
  		BufferedReader br;
  
  		public Scanner(InputStream s){	br = new BufferedReader(new InputStreamReader(s));}
  
  		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();}
  
  
  	}
  }