#include <bits/stdc++.h>
using namespace std;
char d[1000][1000];
int used[1000][1000];
int main() {
  int a, b, c, say = 0;
  cin >> a;
  for (int i = 1; i <= a; i++)
    for (int j = 1; j <= a; j++) cin >> d[i][j];
  for (int i = 1; i <= a; i++) {
    for (int j = 1; j <= a; j++) {
      if (used[i][j] == 0 && d[i][j] == '#') {
        if (d[i + 1][j] == '#' && used[i + 1][j] == 0) say++;
        if (d[i][j + 1] == '#' && used[i][j + 1] == 0) say++;
        if (d[i - 1][j] == '#' && used[i - 1][j] == 0) say++;
        if (d[i][j - 1] == '#' && used[i][j - 1] == 0) say++;
      }
      if (say == 4) {
        used[i + 1][j] = 1;
        used[i][j + 1] = 1;
        used[i - 1][j] = 1;
        used[i][j - 1] = 1;
        used[i][j] = 1;
      }
      say = 0;
    }
  }
  for (int i = 1; i <= a; i++) {
    for (int j = 1; j <= a; j++) {
      if (d[i][j] == '#' && used[i][j] == 0) {
        cout << "NO" << endl;
        return 0;
      }
    }
  }
  cout << "YES" << endl;
  return 0;
}
