#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  int n;
  cin >> n;
  bool t[n][n];
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) {
      char x;
      cin >> x;
      if (x == '#')
        t[i][j] = 1;
      else
        t[i][j] = 0;
    }
  int x[4] = {-1, 1, 0, 0};
  int y[4] = {0, 0, -1, 1};
  for (int i = 1; i < n - 1; i++)
    for (int j = 1; j < n - 1; j++) {
      if (t[i][j] == 1) {
        bool b = true;
        for (int k = 0; k < 4; k++)
          if (t[i + x[k]][j + y[k]] == false) b = false;
        if (b == true) {
          t[i][j] = 0;
          for (int k = 0; k < 4; k++) t[i + x[k]][j + y[k]] = 0;
        }
      }
    }
  bool gogo = true;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++)
      if (t[i][j] == 1) gogo = false;
  if (gogo == true)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
