#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  char grid[n][n];
  int hash_count = 0, cross = 0;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      cin >> grid[i][j];
      if (grid[i][j] == '#') hash_count++;
    }
  }
  for (int i = 0; i < n - 2; i++) {
    for (int j = 0; j < n - 2; j++) {
      if (grid[i][j + 1] == '#' && grid[i + 1][j] == '#' &&
          grid[i + 1][j + 1] == '#' && grid[i + 1][j + 2] == '#' &&
          grid[i + 2][j + 1] == '#') {
        cross += 5;
        grid[i][j + 1] = 'x';
        grid[i + 1][j] = 'x';
        grid[i + 1][j + 1] = 'x';
        grid[i + 1][j + 2] = 'x';
        grid[i + 2][j + 1] = 'x';
      }
    }
  }
  if (hash_count == cross)
    cout << "YES";
  else
    cout << "NO";
  return 0;
}
