Problem:
Score: 300 points

Problem Statement

We have a 3 \times 3 grid. A number c_{i, j} is written in the square (i, j), where (i, j) denotes the square at the i-th row from the top and the j-th column from the left.

According to Takahashi, there are six integers a_1, a_2, a_3, b_1, b_2, b_3 whose values are fixed, and the number written in the square (i, j) is equal to a_i + b_j.

Determine if he is correct.

Constraints

c_{i, j} \ (1 \leq i \leq 3, 1 \leq j \leq 3) is an integer between 0 and 100 (inclusive).

Input

Input is given from Standard Input in the following format:

c_{1,1} c_{1,2} c_{1,3}
c_{2,1} c_{2,2} c_{2,3}
c_{3,1} c_{3,2} c_{3,3}

Output

If Takahashi's statement is correct, print Yes; otherwise, print No.

Sample Input 1

1 0 1
2 1 2
1 0 1

Sample Output 1

Yes

Takahashi is correct, since there are possible sets of integers such as: a_1=0,a_2=1,a_3=0,b_1=1,b_2=0,b_3=1.

Sample Input 2

2 2 2
2 1 2
2 2 2

Sample Output 2

No

Takahashi is incorrect in this case.

Sample Input 3

0 8 8
0 8 8
0 8 8

Sample Output 3

Yes

Sample Input 4

1 8 6
2 9 7
0 7 7

Sample Output 4

No

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;


public class C
{
	public static void Main()
	{	
		string[] args;

		int[,] c = new int[3,3];
		for(int i = 0; i < 3; i++)
		{
			args = Console.ReadLine().Split(' ');
			for(int j = 0; j < 3; j++)
				c[i,j] =  Int32.Parse(args[j]);
		}

		int[] a = new int[3];
		int[] b = new int[3];
		a[0] = 0;
		b[0] = c[0,0];
		b[1] = c[0,1];
		b[2] = c[0,2];
		a[1] = c[1,1] - b[1];
		a[2] = c[2,2] - b[2];

		bool isYes = true;
		for(int i = 0; i < 3; i++)
		{
			for(int j = 0; j < 3; j++)
			{
				if((a[i] + b[j]) != c[i,j])
				{
					isYes = false;
					break;
				}
			}
			if(!isYes)
				break;
		}

		Console.WriteLine(isYes ? "Yes" : "No");
	}	
}