#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, s, t, j;
  char p[100][100];
  for (i = 0; i < 8; i++) {
    scanf("%s", p[i]);
  }
  for (i = 0; i < 8; i++) {
    if (strcmp(p[i], "WBWBWBWB") == 0 || strcmp(p[i], "BWBWBWBW") == 0) {
      t = 0;
    } else {
      t = 1;
      break;
    }
  }
  if (t == 1) {
    printf("NO\n");
  } else {
    printf("YES\n");
  }
  return 0;
}
