#include <bits/stdc++.h>
using namespace std;
int main() {
  string s[101];
  bool vis[101][101];
  memset(vis, 0, sizeof vis);
  int n, ans = 0;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    cin >> s[i];
  }
  for (int i = 1; i < n - 1; ++i) {
    for (int j = 1; j < n - 1; ++j) {
      if (s[i - 1][j] == '#' && !vis[i - 1][j] && s[i + 1][j] == '#' &&
          !vis[i + 1][j] && s[i][j - 1] == '#' && !vis[i][j - 1] &&
          s[i][j + 1] == '#' && !vis[i][j + 1] && s[i][j] == '#' &&
          !vis[i][j]) {
        vis[i - 1][j] = vis[i + 1][j] = vis[i][j - 1] = vis[i][j + 1] =
            vis[i][j] = 1;
      }
    }
  }
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < n; ++j) {
      if (s[i][j] == '#' && !vis[i][j]) {
        printf("NO");
        return 0;
      }
    }
  }
  printf("YES");
  return 0;
}
