#include <bits/stdc++.h>
using namespace std;
inline void inpint(int &n) {
  n = 0;
  register int ch = getchar_unlocked();
  bool sign = 0;
  while (ch < 48 || ch > 57) {
    if (ch == '-') sign = 1;
    ch = getchar_unlocked();
  }
  while (ch >= 48 && ch <= 57) {
    n = (n << 3) + (n << 1) + ch - 48, ch = getchar_unlocked();
  }
  if (sign) n = -n;
}
inline int sqr(int x) { return x * x; }
inline int cube(int x) { return x * x * x; }
inline long long sqrLL(long long x) { return x * x; }
inline long long cubeLL(long long x) { return x * x * x; }
const long long LLINF = 9223372036854775807LL;
const long long LLINF17 = 100000000000000000LL;
const int INF = 2147483647;
const int INF9 = 1000000000;
const int MOD = 1000000007;
const double eps = 1e-7;
const double PI = acos(-1.0);
int dr[] = {1, 0, -1, 0, -1, 1, 1, -1};
int dc[] = {0, -1, 0, 1, 1, 1, -1, -1};
string s;
int main() {
  for (int(i) = (0); (i) < (8); (i)++) {
    cin >> s;
    char prev = 'z';
    for (int(j) = (0); (j) < ((int)(s.length())); (j)++) {
      if (s[j] == prev) {
        puts("NO");
        return 0;
      }
      prev = s[j];
    }
  }
  puts("YES");
  return 0;
}
