#include <bits/stdc++.h>
using namespace std;
using G=vector<vector<int>>;
typedef long long ll;
#define rep(i,l,r) for(int i=(l);i<(r);++i)

int main(){
	int n=3;
	vector<vector<string>> a(n,vector<string>(n));
	rep(i,0,n){string s;cin>>s;rep(j,0,n){a[i][j]=s[j];}}
	bool flg=true;
	rep(i,0,n-1){
		rep(j,0,n){
			if(a[i][j]==a[i+1][j]) flg=false;
			if(a[i][j]==a[i][j+1]) flg=false;
		}
	}
	cout<<(flg?"Yes":"No")<<endl;
}