#include <bits/stdc++.h>
using namespace std;
bool ck[150][150];
int main() {
  int n;
  cin >> n;
  char **a = new char *[n + 2];
  for (int i = 0; i < 2 + n; i++) a[i] = new char[2 + n];
  for (int i = 0; i < n + 2; i++) {
    a[i][0] = '.';
    a[0][i] = '.';
    a[n + 2 - 1][i] = '.';
    a[i][n + 2 - 1] = '.';
    ck[i][0] = true;
    ck[0][i] = true;
    ck[n + 2 - 1][i] = true;
    ck[i][n + 2 - 1] = true;
  }
  int c = 0;
  for (int i = 1; i < n + 1; i++)
    for (int j = 1; j < n + 1; j++) {
      cin >> a[i][j];
      if (a[i][j] == '#') c++;
    }
  for (int i = 1; i < n + 1; i++) {
    for (int j = 1; j < n + 1; j++) {
      if (a[i][j] == '#' && !ck[i][j]) {
        ck[i][j] = true;
        if ((a[i][j + 1] == '#' && a[i][j - 1] == '#' && a[i + 1][j] == '#' &&
             a[i - 1][j] == '#') &&
            (!ck[i][j + 1] && !ck[i][j - 1] && !ck[i + 1][j] &&
             !ck[i - 1][j])) {
          ck[i][j + 1] = true;
          ck[i][j - 1] = true;
          ck[i + 1][j] = true;
          ck[i - 1][j] = true;
        } else
          ck[i][j] = false;
      }
    }
  }
  int t = 0;
  for (int i = 1; i < n + 2 - 1; i++) {
    for (int j = 1; j < n + 2 - 1; j++) {
      if (ck[i][j]) t++;
    }
  }
  if (t == c)
    cout << "YES\n";
  else
    cout << "NO\n";
}
