a=[int(i) for i in input().split()]

if (a[2]+a[0])/2==a[1]:

    print('YES')

else:

    print('NO')
a,b,c=list(map(int,input().split()))

if (a+c)/2==b:

    print('YES')

else:

    print('NO')
a = [int(i) for i in input().split()]
if (a[2] + a[0]) / 2 == a[1]:
    print("YES")
else:
    print("NO")

a, b, c = list(map(int, input().split()))
if (a + c) / 2 == b:
    print("YES")
else:
    print("NO")

-a = [int(i) for i in input().split()] -if (a[2] + a[0]) / 2 == a[1]: +a, b, c = list(map(int, input().split())) +if (a + c) / 2 == b: