#include <bits/stdc++.h>
using namespace std;
string a[105];
int main() {
  int n, i, j;
  scanf("%d", &n);
  for (i = 1; i <= n; i++) cin >> a[i];
  for (i = 2; i < n; i++) {
    for (j = 1; j < n - 1; j++) {
      if (a[i][j] == '#') {
        if (a[i - 1][j] == '#' && a[i][j - 1] == '#' && a[i][j + 1] == '#' &&
            a[i + 1][j] == '#') {
          a[i - 1][j] = a[i][j - 1] = a[i][j] = a[i][j + 1] = a[i + 1][j] = '.';
        }
      }
    }
  }
  for (i = 1; i <= n; i++) {
    for (j = 0; j < n; j++) {
      if (a[i][j] == '#') {
        printf("NO\n");
        return 0;
      }
    }
  }
  printf("YES\n");
  return 0;
}
