#include <bits/stdc++.h>
using namespace std;
void solve() {
  char arr[8][8];
  for (int i = 0; i < 8; i++) {
    for (int j = 0; j < 8; j++) {
      cin >> arr[i][j];
    }
  }
  for (int i = 0; i < 8; i++) {
    for (int j = 0; j < 7; j++) {
      if (arr[i][j] == arr[i][j + 1]) {
        cout << "NO\n";
        return;
      }
    }
  }
  cout << "YES\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long T;
  T = 1;
  for (int t = 0; t < T; t++) {
    solve();
  }
  return 0;
}
