#include <bits/stdc++.h>
using namespace std;
bool row[100][100];
int main() {
  int n;
  cin >> n;
  std::vector<pair<int, int> > v;
  string s[n];
  for (int i = 0; i < n; i++) cin >> s[i];
  int cnt = 0;
  for (int i = 1; i < n - 1; i++) {
    for (int j = 1; j < n - 1; j++) {
      if (s[i][j] == '#') {
        if (s[i][j] == '#' && s[i + 1][j] == '#' && s[i - 1][j] == '#' &&
            s[i][j - 1] == '#' && s[i][j + 1] == '#') {
          s[i][j] = '0';
          s[i + 1][j] = '0';
          s[i][j + 1] = '0';
          s[i][j - 1] = '0';
          s[i - 1][j] = '0';
          row[i][j] = true;
          row[i + 1][j] = true;
          row[i - 1][j] = true;
          row[i][j + 1] = true;
          row[i][j] = true;
          row[i][j - 1] = true;
        }
      }
    }
  }
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (s[i][j] == '#' && row[i][j] == false) {
        cout << "NO\n";
        return 0;
      }
    }
  }
  cout << "YES\n";
}
