#include <bits/stdc++.h>
using namespace std;
int arahx4[] = {0, -1, 0, 1};
int arahy4[] = {-1, 0, 1, 0};
int arahx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
int arahy8[] = {-1, -1, 0, 1, 1, 1, 0, -1};
string s;
int main() {
  char ss[8];
  for (int(i) = (1); (i) <= (8); (i)++) {
    gets(ss);
    s = ss;
    if (s == "WBWBWBWB" || s == "BWBWBWBW") continue;
    puts("NO");
    return 0;
  }
  puts("YES");
  return 0;
}
