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