#include <bits/stdc++.h>
using namespace std;
long long mod = 1e9 + 7;
char mat[105][105];
int vis[105][105];
int main() {
  int n;
  scanf("%d", &(n));
  for (int i = (1); i <= (n); i++)
    for (int j = (1); j <= (n); j++) cin >> mat[i][j];
  for (int i = (1); i <= (n); i++) {
    for (int j = (1); j <= (n); j++) {
      if (vis[i][j] == 1) continue;
      vis[i][j] = 1;
      if (mat[i][j] == '#') {
        if (mat[i + 1][j] == '#' && mat[i + 2][j] == '#' &&
            mat[i + 1][j - 1] == '#' && mat[i + 1][j + 1] == '#' &&
            vis[i + 1][j] == 0 && vis[i + 2][j] == 0 &&
            vis[i + 1][j - 1] == 0 && vis[i + 1][j + 1] == 0) {
          vis[i + 1][j] = 1;
          vis[i + 2][j] = 1;
          vis[i + 1][j - 1] = 1;
          vis[i + 1][j + 1] = 1;
        } else {
          cout << "NO\n";
          return 0;
        }
      }
    }
  }
  cout << "YES\n";
  return 0;
}
