#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  string str[110];
  cin >> n;
  for (int i = 0; i < n; i++) cin >> str[i];
  bool found = true;
  for (int i = 0; i < n - 2 && found; i++) {
    for (int j = 1; j < n - 1 && found; j++) {
      if (str[i][j] == '#') {
        if (str[i + 1][j - 1] != '#' || str[i + 1][j] != '#' ||
            str[i + 1][j + 1] != '#' || str[i + 2][j] != '#')
          found = false;
        else
          str[i][j] = str[i + 1][j - 1] = str[i + 1][j] = str[i + 1][j + 1] =
              str[i + 2][j] = '.';
      }
    }
  }
  if (found) {
    for (int i = 0; i < n && found; i++) {
      for (int j = 0; j < n && found; j++) {
        if (str[i][j] == '#') found = false;
      }
    }
  }
  if (found)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
