#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, flag = 1;
  char a[] = "WBWBWBWB", b[] = "BWBWBWBW";
  char t[10];
  for (i = 0; i < 8; ++i) {
    scanf("%s", t);
    if (strcmp(t, a) && strcmp(t, b)) {
      flag = 0;
    }
  }
  if (flag)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
