#include <bits/stdc++.h>
using namespace std;
void init_ios() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
}
string a = "BWBWBWBW", b = "WBWBWBWB", c;
int main() {
  init_ios();
  bool res = true;
  for (int i = 1; i <= 8; ++i) {
    cin >> c;
    if (c != a && c != b) res = false;
  }
  if (res)
    cout << "YES\n";
  else
    cout << "NO\n";
}
