#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  char square[100][100];
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) {
      cin >> square[i][j];
    }
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) {
      if (square[i][j] == '#') {
        if ((square[i + 1][j] == '#') && (square[i + 1][j - 1] == '#') &&
            (square[i + 1][j + 1] == '#') && (square[i + 2][j] == '#')) {
          square[i + 1][j] = '.';
          square[i][j] = '.';
          square[i + 1][j - 1] = '.';
          square[i + 1][j + 1] = '.';
          square[i + 2][j] = '.';
        } else {
          cout << "NO";
          return 0;
        }
      }
    }
  {
    cout << "YES";
    return 0;
  }
}
