#include <bits/stdc++.h>
using namespace std;
int n;
char arr[109][109];
bool vis[109][109];
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= n; j++) cin >> arr[i][j];
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= n; j++)
      if (arr[i][j] == '#' and vis[i][j] == false and arr[i + 1][j] == '#' and
          vis[i + 1][j] == false and arr[i - 1][j] == '#' and
          vis[i - 1][j] == false and arr[i][j + 1] == '#' and
          vis[i][j + 1] == false and arr[i][j - 1] == '#' and
          vis[i][j - 1] == false)
        vis[i][j] = vis[i][j + 1] = vis[i][j - 1] = vis[i - 1][j] =
            vis[i + 1][j] = true;
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= n; j++)
      if (vis[i][j] == false and arr[i][j] == '#') return cout << "NO", 0;
  cout << "YES";
  return 0;
}
