#include <bits/stdc++.h>
using namespace std;
int main() {
  string s, s1 = "BWBWBWBW", s2 = "WBWBWBWB";
  bool k = true;
  for (int i = 1; i <= 8; i++) {
    cin >> s;
    if ((s == s1) || (s == s2))
      continue;
    else
      k = false;
    break;
  }
  if (k == true)
    cout << "YES\n";
  else
    cout << "NO\n";
}
