#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using ll=long long;
using Graph=vector<vector<int>>;
#define INF 1000000000
#define MOD 998244353
#define MAX 1000000

int main(){
  vector<char> S(9);
  for(int i=0;i<9;i++){
    cin>>S[i];
  }
  for(int i=0;i<8;i++){
    if(S[i]==S[i+1]){
      cout<<"No"<<'\n';
      return 0;
    }
  }
  cout<<"Yes"<<'\n';
}