#include <bits/stdc++.h>
using namespace std;
void solve() {
  int n;
  cin >> n;
  char a[n][n];
  for (int i = 0; i < (n); i++) {
    for (int j = 0; j < (n); j++) cin >> a[i][j];
  }
  long long cnt = 0;
  for (int i = 0; i < (n); i++) {
    for (int j = 0; j < (n); j++) {
      if (a[i][j] == '#') cnt++;
    }
  }
  int x = 0;
  if (cnt == 0)
    cout << "YES" << endl;
  else if (cnt % 5 != 0)
    cout << "NO" << endl;
  else {
    for (int i = 0; i < (n); i++) {
      for (int j = 0; j < (n); j++) {
        if (a[i][j] == '#' && a[i - 1][j] == '#' && a[i][j - 1] == '#' &&
            a[i + 1][j] == '#' && a[i][j + 1] == '#') {
          a[i][j] = '.', a[i - 1][j] = '.', a[i][j - 1] = '.',
          a[i + 1][j] = '.', a[i][j + 1] = '.';
          x++;
        }
      }
    }
    if (x * 5 == cnt)
      cout << "YES" << endl;
    else
      cout << "NO" << endl;
  }
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int t;
  solve();
}
