#include <bits/stdc++.h>   using namespace std;   int main() {     char s[18];     for (int i = 1; i <= 8; i++) {       cin >> s;       bool p = false;       for (int j = 1; j < 8; j++)         if (s[j] == s[j - 1]) {           p = true;           break;         }       if (p) {         cout <<  NO ;         return 0;       }     }     cout <<  YES ;     return 0;   }   