#include <bits/stdc++.h>
using namespace std;
template <class T>
T gcd(T a, T b) {
  return (b == 0) ? a : gcd(b, a % b);
}
template <class T>
T lcm(T a, T b) {
  return a * (b / gcd(a, b));
}
using namespace std;
int main() {
  string S[10];
  int no;
  bool ok = 1;
  for (int i = (0); i < (8); ++i) cin >> S[i];
  for (int i = (0); i < (8); ++i) {
    if (S[i][0] == 'W')
      no = 1;
    else
      no = 0;
    for (int j = (0); j < (8); ++j) {
      if (S[i][j] == 'W' && no == 1)
        no = 0;
      else if (S[i][j] == 'B' && no == 0)
        no = 1;
      else
        ok = 0;
    }
  }
  if (ok)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
