#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  int count = 0;
  cin >> n;
  bool flag = false;
  char a[n][n];
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) {
      cin >> a[i][j];
      if (a[i][j] == '#') count++;
    }
  if (count % 5 == 0) {
    for (int i = 1; i < (n - 1); i++) {
      for (int j = 1; j < (n - 1); j++) {
        if (a[i][j] == '#')
          if (a[i - 1][j] == '#')
            if (a[i + 1][j] == '#')
              if (a[i][j - 1] == '#')
                if (a[i][j + 1] == '#') {
                  a[i][j] = '.';
                  a[i + 1][j] = '.';
                  a[i - 1][j] = '.';
                  a[i][j + 1] = '.';
                  a[i][j - 1] = '.';
                  count -= 5;
                }
      }
      if (count == 0) {
        flag = true;
        break;
      }
    }
  }
  if (flag)
    cout << "YES";
  else
    cout << "NO";
  return 0;
}
