#include <bits/stdc++.h>
using namespace std;
char a[20][20];
int i, j, k = 0;
string s = "WBWBWBWB", s1 = "BWBWBWBW", z[20];
int main() {
  for (i = 1; i <= 8; i++) {
    cin >> z[i];
  }
  for (i = 1; i <= 8; i++) {
    if (z[i] != s && z[i] != s1) {
      cout << "NO";
      return 0;
    }
  }
  cout << "YES";
  return 0;
}
