#include <bits/stdc++.h>
using namespace std;
char mp[200][200];
int main() {
  int n;
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    scanf("%s", mp[i] + 1);
  }
  bool flag = true;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      if (mp[i][j] == '#') {
        if (mp[i - 1][j] == '#' && mp[i + 1][j] == '#' && mp[i][j - 1] == '#' &&
            mp[i][j + 1] == '#') {
          mp[i - 1][j] = ' ', mp[i + 1][j] = ' ', mp[i][j - 1] = ' ',
                 mp[i][j + 1] = ' ', mp[i][j] = ' ';
        }
      }
    }
  }
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      if (mp[i][j] == '#') {
        flag = false;
      }
    }
  }
  if (flag) {
    cout << "YES";
  } else {
    cout << "NO";
  }
  return 0;
}
