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