#include <bits/stdc++.h>
using namespace std;
vector<vector<int> > v;
int n;
int sum, total;
string temp;
int main() {
  cin >> n;
  v.resize(n);
  for (int i = 0; i < n; i++) {
    cin >> temp;
    for (int j = 0; j < n; j++) {
      if (temp[j] == '#') {
        v[i].push_back(1);
        sum++;
      } else
        v[i].push_back(0);
    }
    temp.clear();
  }
  bool shit = true;
  if (sum == 0) {
    cout << "YES";
    shit = false;
  }
  if (sum % 5 != 0 || v[0][0] == 1 || v[n - 1][n - 1] == 1 ||
      v[0][n - 1] == 1 || v[n - 1][0] == 1) {
    shit = false;
    cout << "NO";
  } else {
    total = 0;
    for (int i = 0; i < n - 2; i++) {
      for (int j = 1; j < n; j++) {
        if (j >= n || i >= n) break;
        if (v[i][j] == 1 && v[i + 1][j] == 1 && v[i + 2][j] == 1 &&
            v[i + 1][j - 1] == 1 && v[i + 1][j + 1] == 1) {
          v[i][j] = 2;
          v[i + 1][j] = 2;
          v[i + 2][j] = 2;
          v[i + 1][j + 1] = 2;
          v[i + 1][j - 1] = 2;
          total += 5;
        }
      }
    }
  }
  if (total == sum && shit)
    cout << "YES";
  else {
    if (shit) cout << "NO";
  }
}
