#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, e) for (int i = (int)(s); i < (int)(e); ++i)
#define all(a) (a).begin(),(a).end()

int main() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    
    vector S(3, vector<char>(3));
    rep(i, 0, 3) rep(j, 0, 3) cin >> S[i][j];
    
    bool ok = true;
    rep(i, 0, 3) rep(j, 0, 2) if (S[i][j] == S[i][j + 1]) ok = false;
    rep(i, 0, 2) rep(j, 0, 3) if (S[i][j] == S[i + 1][j]) ok = false;
    
    cout << (ok ? "Yes\n" : "No\n");
}