#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  char mat[n][n];
  int crosses = 0;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) {
      cin >> mat[i][j];
      if (mat[i][j] == '#') crosses++;
    }
  if (crosses % 5 != 0) {
    cout << "NO";
    return 0;
  }
  if (crosses == 0) {
    cout << "YES";
    return 0;
  }
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) {
      if (mat[i][j] == '#') {
        if (i + 2 < n and j - 1 >= 0 and j + 1 < n) {
          if (mat[i + 1][j] == '#' and mat[i + 2][j] == '#' and
              mat[i + 1][j - 1] == '#' and mat[i + 1][j + 1] == '#') {
            mat[i + 1][j] = '!';
            mat[i + 2][j] = '!';
            mat[i + 1][j - 1] = '!';
            mat[i + 1][j + 1] = '!';
          } else {
            cout << "NO";
            return 0;
          }
        } else {
          cout << "NO ";
          return 0;
        }
      }
    }
  cout << "YES";
  return 0;
}
