#問題概要
https://atcoder.jp/contests/abc088/tasks/abc088_c

#考えたこと
c11, c12, c13 = a1+b1, a1+b2, a1+b3
c21, c22, c23 = a2+b1, a2+b2, a2+b3
c31, c32, c33 = a3+b1, a3+b2, a3+b3

よって

c11 + c22 + c33
= c12 + c23 + c31
= c13 + c32 + c21
= a1 + a2 + a3 + b1 + b2 + b3

#提出コード
https://atcoder.jp/contests/abc088/submissions/15778910

test.py

def solve():
    import sys
    s = list(map(int, sys.stdin.read().split()))
    x, y, z = s[0] + s[4] + s[8], s[1] + s[5] + s[6], s[2] + s[3] + s[7]
    if x == y == z:
        print("Yes")
    else:
        print("No")

    return
solve()

#編集中