#include <bits/stdc++.h>
using namespace std;
int main() {
  char p[8][8], u;
  int c = 1;
  for (int i = 0; i < 8; i++) {
    for (int j = 0; j < 8; j++) {
      cin >> p[i][j];
      if (j == 0) {
        u = p[i][j];
      } else {
        if (u == p[i][j]) c = 0;
        u = p[i][j];
      }
    }
  }
  if (c == 1)
    cout << "YES";
  else
    cout << "NO";
  return 0;
}
