#include <bits/stdc++.h>
using namespace std;
char arr[101][101];
int n;
bool is_center(int x, int y) {
  bool b = 1;
  b &= (arr[x][y] == '#' && x - 1 >= 0 && arr[x - 1][y] == '#');
  b &=
      (x + 1 < n && arr[x + 1][y] == '#' && y - 1 >= 0 && arr[x][y - 1] == '#');
  b &= (y + 1 < n && arr[x][y + 1] == '#');
  return b;
}
int main() {
  cin >> n;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) cin >> arr[i][j];
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++)
      if (is_center(i, j))
        arr[i][j] = arr[i - 1][j] = arr[i + 1][j] = arr[i][j - 1] =
            arr[i][j + 1] = '.';
  int counter = 0;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) counter += (arr[i][j] == '#');
  if (counter == 0)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
