#include <bits/stdc++.h>
using namespace std;
char a[105][105];
int main(void) {
  int w = 0, n;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%s", a[i]);
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++)
      if (a[i][j] == '#')
        for (int p = 0; p <= 2; p++)
          for (int q = -1; q <= 1; q++)
            if ((p + q) % 2 == 0 || (p == 1 && q == 0)) {
              if (i + p >= 0 && i + p < n && j + q >= 0 && j + q < n) {
                if (a[i + p][j + q] != '#') w = 1;
                a[i + p][j + q] = '.';
              } else
                w = 1;
            }
  puts(w ? "NO" : "YES");
  return 0;
}
