#include <bits/stdc++.h>
using namespace std;
char grid[200][200];
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      cin >> grid[i][j];
    }
  }
  bool fail = false;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (grid[i][j] == '#') {
        if (grid[i + 1][j] == '#') {
          grid[i + 1][j] = '.';
        } else {
          fail = true;
          break;
        }
        if (grid[i + 2][j] == '#') {
          grid[i + 2][j] = '.';
        } else {
          fail = true;
          break;
        }
        if (grid[i + 1][j + 1] == '#') {
          grid[i + 1][j + 1] = '.';
        } else {
          fail = true;
          break;
        }
        if (grid[i + 1][j - 1] == '#') {
          grid[i + 1][j - 1] = '.';
        } else {
          fail = true;
          break;
        }
        grid[i][j] = '.';
      }
    }
    if (fail) break;
  }
  if (fail)
    cout << "NO" << endl;
  else
    cout << "YES" << endl;
}
