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