#include <bits/stdc++.h>
using namespace std;
int b[105][105], n;
int main() {
  cin >> n;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) {
      char temp;
      cin >> temp;
      if (temp == '#') b[i][j] = 1;
    }
  for (int i = 0; i < n - 2; i++)
    for (int j = 1; j < n - 1; j++)
      if (b[i][j] == 1 && b[i + 1][j - 1] == 1 && b[i + 1][j] == 1 &&
          b[i + 1][j + 1] == 1 && b[i + 2][j] == 1)
        b[i][j] = b[i + 1][j - 1] = b[i + 1][j] = b[i + 1][j + 1] =
            b[i + 2][j] = 0;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++)
      if (b[i][j] == 1) {
        cout << "NO";
        return 0;
      }
  cout << "YES";
  return 0;
}
