#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int i, j, v[n][n];
  char a[n][n];
  for (i = 0; i < n; i++)
    for (j = 0; j < n; j++) cin >> a[i][j];
  for (i = 0; i < n; i++)
    for (j = 0; j < n; j++) v[i][j] = 0;
  for (i = 1; i < n - 1; i++) {
    for (j = 1; j < n - 1; j++) {
      if (v[i][j] == 0 && a[i][j] == '#' && a[i - 1][j] == '#' &&
          a[i + 1][j] == '#' && a[i][j - 1] == '#' && a[i][j + 1] == '#') {
        v[i][j] = v[i + 1][j] = v[i - 1][j] = v[i][j - 1] = v[i][j + 1] = 1;
        a[i][j] = a[i + 1][j] = a[i - 1][j] = a[i][j - 1] = a[i][j + 1] = '.';
      }
    }
  }
  int flag = 0;
  for (i = 0; i < n; i++) {
    for (j = 0; j < n; j++)
      if (a[i][j] == '#') {
        flag = 1;
        break;
      }
    if (flag == 1) break;
  }
  if (flag == 1)
    cout << "NO" << endl;
  else
    cout << "YES" << endl;
}
