#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  char mat[n][n];
  int b = 0;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) {
      cin >> mat[i][j];
      if (mat[i][j] == '#') b++;
    }
  if (b % 5 != 0) {
    cout << "NO" << endl;
    goto kraj;
  } else {
    for (int i = 1; i < n - 1; i++) {
      for (int j = 1; j < n - 1; j++) {
        if (mat[i][j] == '#' && mat[i - 1][j] == '#' && mat[i + 1][j] == '#' &&
            mat[i][j - 1] == '#' && mat[i][j + 1] == '#') {
          mat[i][j] = '.';
          mat[i - 1][j] = '.';
          mat[i + 1][j] = '.';
          mat[i][j - 1] = '.';
          mat[i][j + 1] = '.';
        }
      }
    }
    for (int i = 0; i < n; i++) {
      bool a = false;
      for (int j = 0; j < n; j++) {
        if (mat[i][j] == '#') {
          a = true;
          break;
        }
      }
      if (a) {
        cout << "NO" << endl;
        goto kraj;
      }
    }
  }
  cout << "YES" << endl;
kraj:
  return 0;
}
