#include <bits/stdc++.h>
using namespace std;
int main() {
  vector<char> W1 = {'W', 'B', 'W', 'B', 'W', 'B', 'W', 'B'};
  vector<char> B1 = {'B', 'W', 'B', 'W', 'B', 'W', 'B', 'W'};
  vector<char> test;
  int sumW1 = 0, sumB1 = 0;
  char a;
  for (int i = 0; i < 8; i++) {
    for (int I = 0; I < 8; I++) {
      cin >> a;
      test.push_back(a);
    }
    if (test == W1) {
      sumW1 += 1;
    }
    if (test == B1) {
      sumB1 += 1;
    }
    test.clear();
  }
  if (sumW1 + sumB1 == 8)
    cout << "YES";
  else
    cout << "NO";
}
