#include <bits/stdc++.h>
int cmp(const void *a, const void *b) { return *(int *)a - *(int *)b; }
using namespace std;
int main() {
  int n, i, j, flag, sum;
  char ch[105][105];
  while (~scanf("%d", &n)) {
    getchar();
    memset(ch, '.', sizeof(ch));
    sum = flag = 0;
    for (i = 1; i <= n; i++) {
      for (j = 1; j <= n; j++) {
        scanf("%c", &ch[i][j]);
        if (ch[i][j] == '#') sum++;
      }
      getchar();
    }
    if (sum % 5) {
      printf("NO\n");
    } else {
      for (i = 1; i <= n; i++) {
        for (j = 1; j <= n; j++) {
          if (ch[i][j] == '#' && ch[i - 1][j] == '#' && ch[i + 1][j] == '#' &&
              ch[i][j - 1] == '#' && ch[i][j + 1] == '#') {
            ch[i][j] = ch[i - 1][j] = ch[i + 1][j] = ch[i][j - 1] =
                ch[i][j + 1] = '.';
            flag++;
          }
        }
      }
      if (flag == sum / 5) {
        printf("YES\n");
      } else {
        printf("NO\n");
      }
    }
  }
  return 0;
}
