#!/usr/bin/env PyPy3

from collections import Counter, defaultdict, deque
import itertools
import re
import math
from functools import reduce
import operator
import bisect
from heapq import *
import functools
mod=998244353

import sys
input=sys.stdin.readline
s=[input().rstrip() for _ in range(3)]
if s[0][0] == s[0][1]:
    print('No')
else:
    for i in range(3):
        for j in range(3):
            if (i + j) % 2:
                if s[i][j] != s[0][1]:
                    print('No')
                    exit()
            else:
                if s[i][j] != s[0][0]:
                    print('No')
                    exit()
    print('Yes')