#include <bits/stdc++.h>
using namespace std;
int n;
char mas[100][100];
void output() {
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < n; ++j) {
      cout << mas[i][j] << " ";
    }
    cout << endl;
  }
  cout << endl;
}
int main() {
  bool ok = true;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < n; ++j) {
      cin >> mas[i][j];
    }
  }
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < n; ++j) {
      if (mas[i][j] == '#') {
        if (i + 1 < n && mas[i + 1][j] == '#')
          mas[i + 1][j] = '.';
        else
          ok = false;
        if (i + 2 >= 0 && mas[i + 2][j] == '#')
          mas[i + 2][j] = '.';
        else
          ok = false;
        if (j + 1 < n && i + 1 < n && mas[i + 1][j + 1] == '#')
          mas[i + 1][j + 1] = '.';
        else
          ok = false;
        if (j - 1 >= 0 && i + 1 < n && mas[i + 1][j - 1] == '#')
          mas[i + 1][j - 1] = '.';
        else
          ok = false;
        mas[i][j] = '.';
      }
    }
    if (!ok) break;
  }
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < n; ++j) {
      if (mas[i][j] == '#') ok = false;
    }
  }
  if (ok)
    cout << "YES";
  else
    cout << "NO";
  return 0;
}
