#include <bits/stdc++.h>
using namespace std;
string board[8];
int main() {
  for (int i = 0; i < 8; ++i) cin >> board[i];
  const char* s = "WB";
  for (int i = 0; i < 8; ++i) {
    int c = board[i][0] == 'B';
    for (int j = 1; j < 8; ++j) {
      if (board[i][j] != s[(c + j) % 2]) {
        cout << "NO\n";
        return 0;
      }
    }
  }
  cout << "YES\n";
  return 0;
}
