#include <bits/stdc++.h>
using namespace std;
char a[8][8];
int i, j;
int main() {
  for (i = 0; i < 8; i++)
    for (j = 0; j < 8; j++) cin >> a[i][j];
  for (i = 0; i < 8; i++)
    for (j = 0; j < 7; j++)
      if (a[i][j] == a[i][j + 1]) {
        cout << "NO";
        exit(0);
      }
  cout << "YES";
  return 0;
}
