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