#include <bits/stdc++.h>
using namespace std;
int main() {
  string a;
  int flag = 0;
  for (int k = 0; k < 8; k++) {
    cin >> a;
    if (a == "WBWBWBWB" || a == "BWBWBWBW") {
    } else {
      flag = 1;
      break;
    }
  }
  if (flag == 1) {
    cout << "NO" << endl;
  } else {
    cout << "YES" << endl;
  }
}
