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 Common Lisp (SBCL 1.1.14) (judge verdict: Accepted)

(let ((c (make-array '(3 3) :element-type 'integer
                            :adjustable t))
      diff1
      diff2
      (ans "Yes"))
  (dotimes (i 3)
    (dotimes (j 3)
      (setf (aref c i j) (read))))
  (setf diff1 (- (aref c 2 1) (aref c 2 0)))
  (setf diff2 (- (aref c 2 2) (aref c 2 1)))
  (dotimes (i 2)
    (if (or (not (equal diff1 (- (aref c i 1) (aref c i 0)))) (not (equal diff2 (- (aref c i 2) (aref c i 1))))) (setf ans "No")))
  (setf diff1 (- (aref c 1 2) (aref c 0 2)))
  (setf diff2 (- (aref c 2 2) (aref c 1 2)))
  (dotimes (i 2)
    (if (or (not (equal diff1 (- (aref c 1 i) (aref c 0 i)))) (not (equal diff2 (- (aref c 2 i) (aref c 1 i))))) (setf ans "No")))
  (format t "~A~%" ans))