#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n;
  cin >> n;
  vector<string> cross(n);
  for (int i = 0; i < n; i++) cin >> cross[i];
  int dx[5] = {0, 0, 0, -1, 1};
  int dy[5] = {0, -1, 1, 0, 0};
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      for (int k = 0; k < 5; k++) {
        int x = i + dx[k], y = j + dy[k];
        if (x < 0 || y < 0 || x >= n || y >= n || cross[x][y] == '.') break;
        if (k == 4) {
          for (int l = 0; l < 5; l++) {
            int x = i + dx[l], y = j + dy[l];
            cross[x][y] = '.';
          }
        }
      }
    }
  }
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) {
      if (cross[i][j] == '#') {
        cout << "NO\n";
        return 0;
      }
    }
  cout << "YES\n";
  return 0;
}
