#include <bits/stdc++.h>
using namespace std;

int main()
{
	vector<string> S( 3 );
	cin >> S[0] >> S[1] >> S[2];

	string ans = "Yes";
	for( int i = 0; i < 3; i++ ) {
		for( int j = 0; j < 3; j++ ) {
			if( i + 1 < 3 && S[i][j] == S[i + 1][j] ) ans = "No";
			if( j + 1 < 3 && S[i][j] == S[i][j + 1] ) ans = "No";
		}
	}

	cout << ans << endl;
}