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 (GCC 5.4.1) (judge verdict: Accepted)


#include <stdio.h>

int is_true(int c[3][3])
{
    int i, j;

    for (i = 0; i < 2; i++) {
        for (j = 0; j < 2; j++) {
            if (c[i][j] - c[i + 1][j] != c[i][j + 1] - c[i + 1][j + 1]) {
                return 0;
            }
        }

        for (j = 0; j < 2; j++) {
            if (c[j][i] - c[j][i + 1] != c[j + 1][i] - c[j + 1][i + 1]) {
                return 0;
            }
        }
    }

    return 1;
}

int main(void)
{
    int c[3][3];

    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < 3; j++) {
            scanf("%d", &c[i][j]);
        }
    }

    if (is_true(c)) {
        printf("Yes\n");
    } else {
        printf("No\n");
    }

    return 0;
}