#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  char ch[n][n];
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) cin >> ch[i][j];
  }
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (ch[i][j] == '#' && ch[i + 1][j] == '#' && ch[i + 2][j] == '#' &&
          ch[i + 1][j - 1] == '#' && ch[i + 1][j + 1] == '#') {
        ch[i][j] = ch[i + 1][j] = ch[i + 2][j] = ch[i + 1][j - 1] =
            ch[i + 1][j + 1] = '.';
      } else if (ch[i][j] == '.')
        continue;
      else {
        cout << "NO"
             << "\n";
        return 0;
      }
    }
  }
  cout << "YES"
       << "\n";
  return 0;
}
