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