#include <bits/stdc++.h>
using namespace std;
long long M = 1e9 + 7;
void solve() {
  long long n;
  cin >> n;
  vector<vector<long long> > a(n, vector<long long>(n, 0));
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) {
      char c;
      cin >> c;
      if (c == '#') a[i][j] = 1;
    }
  for (int i = 1; i < n - 1; i++) {
    for (int j = 1; j < n - 1; j++) {
      if (a[i][j] == 1 && a[i - 1][j] == 1 && a[i + 1][j] == 1 &&
          a[i][j - 1] == 1 && a[i][j + 1] == 1) {
        a[i][j] = 0;
        a[i + 1][j] = 0;
        a[i - 1][j] = 0;
        a[i][j - 1] = 0;
        a[i][j + 1] = 0;
      }
    }
  }
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++)
      if (a[i][j]) {
        cout << "NO"
             << "\n";
        return;
      }
  cout << "YES"
       << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
