#include <bits/stdc++.h>
using namespace std;
const int N = 100 + 11;
char s[N][N];
int a[N][N];
int main() {
  ios_base ::sync_with_stdio(false);
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      cin >> s[i][j];
      if (s[i][j] == '#')
        a[i][j] = 1;
      else
        a[i][j] = 0;
    }
  }
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (a[i][j]) {
        if (i > n - 2 || j > n - 1) a[i][j]--;
        a[i][j]--;
        a[i + 1][j]--;
        a[i + 2][j]--;
        a[i + 1][j - 1]--;
        a[i + 1][j + 1]--;
      }
    }
  }
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (a[i][j]) {
        cout << "NO" << endl;
        return 0;
      }
    }
  }
  cout << "YES" << endl;
  return 0;
}
