#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  char arr[n][n];
  int f[n][n];
  int count = 0;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      cin >> arr[i][j];
      if (arr[i][j] == '#') {
        count++;
      }
      f[i][j] = 0;
    }
  }
  int c = 0;
  for (int i = 0; i + 2 < n; i++) {
    for (int j = 0; j + 1 < n; j++) {
      if (arr[i][j] == '#' && f[i][j] == 0) {
        if (arr[i + 1][j - 1] == '#' && f[i + 1][j - 1] == 0 &&
            arr[i + 1][j] == '#' && f[i + 1][j] == 0 &&
            arr[i + 1][j + 1] == '#' && f[i + 1][j + 1] == 0 &&
            arr[i + 2][j] == '#' && f[i + 2][j] == 0) {
          f[i][j] = 1;
          f[i + 1][j - 1] = 1;
          f[i + 1][j] = 1;
          f[i + 1][j + 1] = 1;
          f[i + 2][j] = 1;
          c++;
        } else {
          c = -1;
          break;
        }
      }
      if (c == -1) {
        break;
      }
    }
    if (c == -1) {
      break;
    }
  }
  if (count % 5 == 0 && count / 5 == c) {
    cout << "YES" << endl;
  } else {
    cout << "NO" << endl;
  }
}
