#include <bits/stdc++.h>
using namespace std;
string s;
int i;
int main() {
  string ans = "YES";
  for (i = 1; i <= 8; i++) {
    cin >> s;
    if (s != "WBWBWBWB" && s != "BWBWBWBW") ans = "NO";
  }
  cout << ans << endl;
}
