#pragma GCC optimize("Ofast")
#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <queue>
#include <cstdio>
#include <ctime>
#include <assert.h>
#include <chrono>
#include <random>
#include <numeric>
#include <set>
#include <deque>
#include <stack>
#include <sstream>
#include <utility>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
#include <tuple>
#include <array>
#include <bitset>
using namespace std;
typedef long long int ll;
typedef unsigned long long ull;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll myRand(ll B) {
    return (ull)rng() % B;
}
inline double time() {
    return static_cast<long double>(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count()) * 1e-9;
}

bool solve(){
    string s[3];
    for(int i=0;i<3;i++){
        cin >> s[i];
    }
    for(int i=0;i<3;i++){
        for(int j=0;j<3;j++){
            if(s[i][j] != ((i+j)%2==0?s[0][0]:s[0][1])){
                return false;
            }
        }
    }
    return (s[0][0] != s[0][1]);
}

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    if(solve()){
        cout << "Yes" << endl;
    }
    else{
        cout << "No" << endl;
    }

}