#include <bits/stdc++.h>
using namespace std;
char cross[101][101];
int main() {
  int n;
  while (cin >> n) {
    for (int i = 0; i < n; i++)
      for (int j = 0; j < n; j++) cin >> cross[i][j];
    int ok = 0;
    for (int i = 1; i < n - 1; i++) {
      for (int j = 1; j < n - 1; j++) {
        if (cross[i][j] == '#') {
          if (cross[i][j] == '#' && cross[i - 1][j] == '#' &&
              cross[i][j - 1] == '#' && cross[i][j + 1] == '#' &&
              cross[i + 1][j] == '#') {
            cross[i][j] = 'a';
            cross[i - 1][j] = 'a';
            cross[i][j - 1] = 'a';
            cross[i][j + 1] = 'a';
            cross[i + 1][j] = 'a';
          }
        }
      }
    }
    for (int i = 0; i < n; i++)
      for (int j = 0; j < n; j++)
        if (cross[i][j] == '#') {
          ok = 1;
          break;
          break;
        }
    if (ok == 0)
      cout << "YES" << endl;
    else
      cout << "NO" << endl;
  }
  return 0;
}
