#include <bits/stdc++.h>
char board[110][110];
int main() {
  int n, i, j;
  scanf("%d", &n);
  for (i = 0; i < n; i++) {
    scanf("%s", &board[i]);
  }
  for (i = 1; i < n - 1; i++) {
    for (j = 1; j < n - 1; j++) {
      if (board[i][j] == '#' && board[i - 1][j] == '#' &&
          board[i + 1][j] == '#' && board[i][j - 1] == '#' &&
          board[i][j + 1] == '#') {
        board[i][j] = '.';
        board[i - 1][j] = '.';
        board[i + 1][j] = '.';
        board[i][j - 1] = '.';
        board[i][j + 1] = '.';
      }
    }
  }
  for (i = 0; i < n; i++) {
    for (j = 0; j < n; j++) {
      if (board[i][j] == '#') {
        printf("NO\n");
        break;
      }
    }
    if (j != n) break;
  }
  if (i == n) printf("YES\n");
  return 0;
}
