#include <bits/stdc++.h>
using namespace std;
const int MAXN = 110;
bool belongs[MAXN][MAXN];
char mp[MAXN][MAXN];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      belongs[i][j] = false;
      cin >> mp[i][j];
    }
  }
  for (int i = 1; i <= n - 2; i++) {
    for (int j = 2; j <= n - 1; j++) {
      if ((!belongs[i][j] && mp[i][j] == '#') &&
          (!belongs[i + 1][j] && mp[i + 1][j] == '#') &&
          (!belongs[i + 2][j] && mp[i + 2][j] == '#') &&
          (!belongs[i + 1][j - 1] && mp[i + 1][j - 1] == '#') &&
          (!belongs[i + 1][j + 1] && mp[i + 1][j + 1] == '#')) {
        belongs[i][j] = true;
        belongs[i + 1][j] = true;
        belongs[i + 2][j] = true;
        belongs[i + 1][j - 1] = true;
        belongs[i + 1][j + 1] = true;
      }
    }
  }
  bool ans = true;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      if ((belongs[i][j] && mp[i][j] == '.') ||
          (!belongs[i][j] && mp[i][j] == '#'))
        ans = false;
    }
  }
  puts(ans ? "YES" : "NO");
  return 0;
}
