#include <bits/stdc++.h>
using namespace std;
char grid[100][100];
int aux[100][100];
bool check(int i, int j) {
  if (grid[i][j] == '#' && aux[i][j] == 0)
    return true;
  else
    return false;
}
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) {
      cin >> grid[i][j];
      aux[i][j] = 0;
    }
  int c = 1;
  for (int i = 1; i < n - 1; i++)
    for (int j = 1; j < n - 1; j++) {
      if (check(i, j) && check(i - 1, j) && check(i + 1, j) &&
          check(i, j - 1) && check(i, j + 1)) {
        aux[i][j] = aux[i - 1][j] = aux[i + 1][j] = aux[i][j - 1] =
            aux[i][j + 1] = c;
        c++;
      }
    }
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++)
      if (aux[i][j] == 0 && grid[i][j] == '#') {
        cout << "NO";
        return 0;
      }
  cout << "YES";
  return 0;
}
