#include <bits/stdc++.h>
using namespace std;
const int MAX = 110;
int a[MAX][MAX];
bool check[MAX][MAX];
int main() {
  int n, ans = 0;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    string x;
    cin >> x;
    for (int j = 0; j < x.size(); j++) {
      a[i][j + 1] = x[j];
      if (x[j] == '#') {
        check[i][j + 1] = 1;
        ans++;
      }
    }
  }
  if (ans % 5 != 0) {
    cout << "NO\n";
    return 0;
  }
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      if (check[i][j] == 1 && a[i][j] == '#') {
        if (check[i + 1][j] && check[i + 1][j + 1] && check[i + 1][j - 1] &&
            check[i + 2][j]) {
          check[i + 1][j] = 0;
          check[i + 1][j + 1] = 0;
          check[i + 1][j - 1] = 0;
          check[i + 2][j] = 0;
          check[i][j] = 0;
        } else {
          cout << "NO\n";
          return 0;
        }
      }
    }
  }
  cout << "YES\n";
}
