#include <bits/stdc++.h>
using namespace std;
string s[101];
string s1, s2;
int n;
int ans;
int main() {
  int i, j, k;
  n = 8;
  s1 = "WBWBWBWB";
  s2 = "BWBWBWBW";
  for (i = 1; i <= n; i++) {
    cin >> s[i];
    if ((s1 != s[i]) && (s2 != s[i])) {
      ans = 1;
    }
  }
  if (!ans) {
    cout << "YES" << endl;
  } else
    cout << "NO" << endl;
  return 0;
}
