#include <bits/stdc++.h>
using namespace std;
int main() {
  string s1 = "WBWBWBWB";
  string s2 = "BWBWBWBW";
  string s;
  for (int i = 0; i < 8; i++) {
    cin >> s;
    if (s != s1 && s != s2) {
      cout << "NO";
      return 0;
    }
  }
  cout << "YES";
  return 0;
}
