#include <bits/stdc++.h>
using namespace std;
int n;
string grid[100];
int di[] = {1, 1, 2, 1};
int dj[] = {-1, 0, 0, 1};
bool check() {
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (grid[i][j] == '.') continue;
      for (int d = 0; d < 4; d++) {
        int ni = i + di[d];
        int nj = j + dj[d];
        if (ni >= n || nj < 0 || nj >= n) return false;
        if (grid[ni][nj] == '.') return false;
        grid[ni][nj] = '.';
      }
    }
  }
  return true;
}
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) cin >> grid[i];
  cout << (check() ? "YES" : "NO") << endl;
  return 0;
}
