#include <bits/stdc++.h>
using namespace std;
char s[200][200];
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) cin >> s[i][j];
  for (int i = 1; i < n - 1; i++)
    for (int j = 1; j < n - 1; j++)
      if (s[i][j] == '#' && s[i + 1][j] == '#' && s[i][j + 1] == '#')
        if (s[i - 1][j] == '#' && s[i][j - 1] == '#')
          s[i][j] = s[i + 1][j] = s[i][j + 1] = s[i][j - 1] = s[i - 1][j] = '.';
  int check = 0;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++)
      if (s[i][j] == '#') check = 1;
  if (check == 1)
    cout << "NO";
  else
    cout << "YES";
  return 0;
}
