Problem: The Human-Cow Confederation (HC2), led by Heidi, has built a base where people and cows can hide, guarded from zombie attacks. The entrance to the base is protected by an automated gate which performs a kind of a Turing test: it shows the entering creature a photograph and asks them whether the top and bottom halves of this photograph have been swapped or not. A person (or even a cow) will have no problem answering such questions; on the other hand, a zombie would just randomly smash one of the two buttons.

The creature is asked a series of such questions. If at least 75% of them are answered correctly, the gate is unlocked; otherwise, a side door opens, beneath which a huge fan is spinning...

Heidi is now building a robot army to fight the zombies, and she wants the robots to also be able to enter the base. You are tasked with programming them to distinguish the images.

<image>

The first two images from the test set. The first picture has been rearranged, but not the second.

Input

The first line of the input contains the number q of questions (1 ≤ q ≤ 220). After that, q questions follow, each of which in the format described below.

The first line of every question contains two space-separated integers h and w (1 ≤ h, w ≤ 600) – the height (number of rows) and width (number of columns) of the photograph. (Most photographs are roughly 200 × 300.) After this, h lines follow, each describing a single row of the picture. The picture is monochrome (in shades of grey). Its i-th row is described by w space-separated integers aij (j = 1, ..., w), where aij is the brightness of the corresponding pixel (0 ≤ aij < 256, where 0 is black and 255 is white).

Each picture will be either a real-life photograph, or a real-life photograph which has been broken up into two pieces and rearranged. More precisely, in the latter case, the topmost <image> rows have been moved to the bottom of the picture. It is guaranteed that h is even.

There is only a single input file to be processed, called all.in, and it is downloadable from the online judge. You are also a given another input file, called sample.in, which contains the first 20 pictures from all.in; you are provided the correct answers for sample.in in sample.out. You are also given a directory easy_bmp, which contains the first 50 input photographs in the form of .bmp image files, as well as a directory easy_sample_original_bmp, which contains the first 20 images before rearrangement. Check the notes for the download links.

Output

Your program should print q lines. The i-th line should contain your answer for the i-th question: YES if the photograph has been rearranged and NO otherwise. Your answers will be accepted if they all conform to this format and if at least 75% of them are correct.

Because the input is rather huge, feel free to process it locally and submit just your precomputed answers (i.e., a program which just prints your output for the input file all.in).

Note

The link to download all necessary files is http://assets.codeforces.com/files/690/easy_contestant_package.zip

Solution (in JAVA):

Solution:
import java.io.*;

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
		
		String line = bf.readLine();
		
		int n = Integer.parseInt(line);
		
		for(int i = 0 ; i < n ; i++){
			String[] tmp = bf.readLine().split(" ");
			int h = Integer.parseInt(tmp[0]);
			int w = Integer.parseInt(tmp[1]);
			
			int[][] mat = new int[h][w];
			
			
			for(int j = 0 ; j < h ; j++){
				tmp = bf.readLine().split(" ");
				for(int k = 0 ; k < w ; k++){
					mat[j][k] = Integer.parseInt(tmp[k]);
				}
			}
			
			int mid = h/2;
			
			int br = 0;
			
			int diff = 0;
			int diff2 = 0;
			
			for(int j = 0 ; j < w ; j++){
				if(Math.abs(mat[mid][j] - mat[mid-1][j]) > 30){
					br++;
					diff2 += Math.abs(mat[mid][j] - mat[mid-1][j]);
					diff2 -= 30;
				}
				diff += Math.abs(mat[mid][j] - mat[mid-1][j]);
			}
			int yes = 0;
//			int no = 0;
			
			if(br > (w/3)){
				yes++;
//				System.out.print("YES ");
			}
//			else System.out.print("NO ");
			
			if( (diff/w) > 20){
				yes++;
//				System.out.print("YES ");
			}
//			else System.out.print("NO ");
			
			if( (diff2/w) > 0){
				yes++;
//				System.out.println("YES ");
			}
//			else System.out.println("NO ");
			
			if(yes>1) System.out.println("YES");
			else System.out.println("NO");
		}
	}
}