#include <bits/stdc++.h>
using namespace std;
int main() {
  string row[] = {"WBWBWBWB", "BWBWBWBW"};
  string tab[10];
  bool R = true;
  for (int i = 0; i < 8; i++)
    getline(cin, tab[i]), R &= (tab[i] == row[0] || tab[i] == row[1]);
  printf("%s\n", R ? "YES" : "NO");
  return 0;
}
