#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  string kelma[n];
  for (int i = 0; i < n; i++) cin >> kelma[i];
  for (int i = 1; i < n - 1; i++) {
    for (int j = 1; j < n - 1; j++) {
      if (kelma[i][j] == '#') {
        if (kelma[i - 1][j] == '#' and kelma[i + 1][j] == '#' and
            kelma[i][j - 1] == '#' and kelma[i][j + 1] == '#') {
          kelma[i - 1][j] = '.';
          kelma[i + 1][j] = '.';
          kelma[i][j - 1] = '.';
          kelma[i][j + 1] = '.';
          kelma[i][j] = '.';
        }
      }
    }
  }
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++)
      if (kelma[i][j] == '#') {
        cout << "NO" << endl;
        return 0;
      }
  cout << "YES" << endl;
  return 0;
}
