#include <bits/stdc++.h>
using namespace std;
int a[55][55];
int flag;
int main() {
  int n, m = 0;
  cin >> n;
  char c;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      cin >> c;
      if (c == '#') {
        a[i][j] = 1;
      }
    }
  }
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      m = 0;
      if (a[i][j] == 1) {
        if (a[i - 1][j] == 1) m++;
        if (a[i + 1][j - 1] == 1) m++;
        if (a[i][j - 1] == 1) m++;
        if (a[i][j + 1] == 1) m++;
      }
      if (m == 0) {
        flag = 1;
        break;
        break;
      }
    }
  }
  if (flag)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
  return 0;
}
