#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  int n;
  cin >> n;
  vector<string> v(n);
  for (int i = 0; i < n; i++) cin >> v[i];
  for (int i = 1; i < n - 1; i++) {
    for (int j = 1; j < n - 1; j++) {
      if (v[i][j] == '#' and v[i + 1][j] == '#' and v[i][j + 1] == '#' and
          v[i][j - 1] == '#' and v[i - 1][j] == '#') {
        v[i][j] = 'a';
        v[i + 1][j] = 'a';
        v[i][j + 1] = 'a';
        v[i][j - 1] = 'a';
        v[i - 1][j] = 'a';
      }
    }
  }
  int c = 0;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++)
      if (v[i][j] == '#') {
        c = 1;
        break;
      }
  if (c)
    cout << "NO" << endl;
  else
    cout << "YES" << endl;
  return 0;
}
