#include <bits/stdc++.h>
using namespace std;
int main() {
  char a[10] = "BWBWBWBW", c[10], *p;
  for (int i = 1; i <= 8; i++) {
    cin >> c;
    p = c;
    if (c[0] == 'W') {
      c[8] = 'W';
      p++;
    }
    if (strcmp(a, p)) {
      cout << "NO";
      return 0;
    }
  }
  cout << "YES";
  return 0;
}
