#include <bits/stdc++.h>
int main() {
  int n;
  std::string desk[100];
  std::cin >> n;
  for (int i = 0; i < n; ++i) std::cin >> desk[i];
  if ((desk[0][0] == '#') || (desk[0][n - 1] == '#') ||
      (desk[n - 1][0] == '#') || (desk[n - 1][n - 1] == '#')) {
    std::cout << "NO";
    return 0;
  }
  for (int i = 0; i < n - 2; ++i)
    for (int j = 1; j < n - 1; ++j)
      if (desk[i][j] == '#')
        if ((desk[i + 1][j - 1] == '#') && (desk[i + 1][j] == '#') &&
            (desk[i + 1][j + 1] == '#') && (desk[i + 2][j] == '#')) {
          desk[i][j] = '.';
          desk[i + 1][j - 1] = '.';
          desk[i + 1][j] = '.';
          desk[i + 1][j + 1] = '.';
          desk[i + 2][j] = '.';
        } else {
          std::cout << "NO";
          return 0;
        }
  for (int i = 1; i < 3; ++i)
    for (int j = 0; j < n; ++j)
      if (desk[n - i][j] == '#') {
        std::cout << "NO";
        return 0;
      }
  std::cout << "YES";
  return 0;
}
