#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c = 0, d, e, f, g, h, arr[100][100], n, m, p, t;
  cin >> n;
  char ch;
  getchar();
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      scanf("%c", &ch);
      if (ch == '#') {
        arr[i][j] = 1;
        c++;
      } else {
        arr[i][j] = -1;
      }
    }
    getchar();
  }
  int l = 0;
  for (int i = 1; i < n; i++) {
    for (int j = 1; j < n; j++) {
      if (arr[i][j] > -1) {
        if (i - 1 >= 0 && i + 1 < n && j - 1 >= 0 && j + 1 < n &&
            arr[i - 1][j] > -1 && arr[i + 1][j] > -1 && arr[i][j - 1] > -1 &&
            arr[i][j + 1] > -1) {
          if (arr[i][j - 1] > 0 && arr[i][j + 1] > 0 && arr[i - 1][j] > 0 &&
              arr[i + 1][j] && arr[i][j] > 0) {
            arr[i - 1][j] = 0;
            arr[i + 1][j] = 0;
            arr[i][j - 1] = 0;
            arr[i][j + 1] = 0;
            arr[i][j] = 0;
            l++;
          }
        }
      }
    }
  }
  if (l * 5 == c)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
