#include <bits/stdc++.h>
using namespace std;
char g[102][102];
int dx[] = {2, 1, 1, 1}, dy[] = {0, 0, 1, -1};
int n;
bool va(int i, int j) { return (i < 1 || j < 1 || i > n || j > n ? 0 : 1); }
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= n; j++) cin >> g[i][j];
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      if (g[i][j] == '#') {
        g[i][j] = '.';
        if (j == 1 || j == n || i >= n - 1) {
          cout << "NO\n";
          return 0;
        }
        for (int k = 0; k < 4; k++) {
          int x = i + dx[k], y = j + dy[k];
          if (va(x, y) && g[x][y] == '#') {
            g[x][y] = '.';
          } else if (va(x, y)) {
            cout << "NO\n";
            return 0;
          }
        }
      }
    }
  }
  cout << "YES\n";
  return 0;
}
