#include <bits/stdc++.h>
int main(void) {
  char b = 'B', w = 'W', c;
  char board[8][16];
  int i, j;
  int flg = 0;
  for (i = 0; i < 8; i++) scanf("%8s%*c", board[i]);
  for (i = 0; i < 8; i++) {
    c = board[i][0];
    for (j = 1; j < 8; j++) {
      if (c == board[i][j]) flg++;
      c = board[i][j];
    }
  }
  if (!flg)
    puts("YES");
  else
    puts("NO");
  return 0;
}
