#include <bits/stdc++.h>
using namespace std;
inline long long powmod(long long x, long long n, long long _mod) {
  long long res = 1;
  while (n) {
    if (n & 1) res = (res * x) % _mod;
    x = (x * x) % _mod;
    n >>= 1;
  }
  return res;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  char s[10][10];
  for (int i = 0; i < 8; ++i)
    for (int j = 0; j < 8; ++j) cin >> s[i][j];
  for (int i = 0; i < 8; ++i) {
    for (int j = 0; j < 7; ++j) {
      if (s[i][j] == s[i][j + 1]) {
        cout << "NO\n";
        return 0;
      }
    }
  }
  cout << "YES\n";
  return 0;
}
