#include <bits/stdc++.h>
using namespace std;
void pr(char a[][101], int n) {
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      printf("%c ", a[i][j]);
    }
    printf("\n");
  }
  printf("\n\n");
}
int main() {
  int n, i, j, c = 0;
  char a[101][101], ch;
  scanf("%d", &n);
  scanf("%c", &ch);
  for (i = 0; i < n; i++) {
    for (j = 0; j < n; j++) {
      scanf("%c", &a[i][j]);
      if (a[i][j] == '#') c++;
    }
    scanf("%c", &ch);
  }
  for (i = 0; i < n; i++) {
    for (j = 0; j < n; j++) {
      if (a[i][j] == '#' && i > 0 && i < n - 1 && j > 0 && j < n - 1) {
        if (a[i + 1][j] == '#' && a[i - 1][j] == '#' && a[i][j - 1] == '#' &&
            a[i][j + 1] == '#') {
          a[i][j] = a[i + 1][j] = a[i - 1][j] = a[i][j - 1] = a[i][j + 1] = '.';
          c = c - 5;
        }
      }
    }
  }
  if (c)
    cout << "NO" << endl;
  else
    cout << "YES" << endl;
  return 0;
}
