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.Linq;
using System.Collections.Generic;

class Program {
    static void Main(string[] args) {
        var a = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
        var b = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
        var c = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
        var d = new int[9];
        a.CopyTo(d, 0);
        b.CopyTo(d, 3);
        c.CopyTo(d, 6);
        bool flag = false;
        if (d[0] - d[1] == d[3] - d[4] && d[0] - d[1] == d[6] - d[7] && d[1] - d[2] == d[4] - d[5] && d[1] - d[2] == d[7] - d[8] && d[0] - d[3] == d[1] - d[4] && d[0] - d[3] == d[2] - d[5] && d[3] - d[6] == d[4] - d[7] && d[3] - d[6] == d[5] - d[8]) {
            flag = true;
        }
        Console.WriteLine(flag ? "Yes" : "No");
    }
}