#include <bits/stdc++.h>
using namespace std;
int main() {
  bool flag = true;
  for (int i = 0; i < 8; i++) {
    char prev;
    cin >> prev;
    for (int j = 1; j < 8; j++) {
      char ch;
      cin >> ch;
      if (ch == prev) flag = false;
      prev = ch;
    }
  }
  if (flag)
    cout << "YES";
  else
    cout << "NO";
  return 0;
}
