#include <bits/stdc++.h>
using namespace std;
char g[100][105];
int main() {
  int n, i, j, k, dx[] = {0, 0, 1, -1}, dy[] = {1, -1, 0, 0};
  cin >> n;
  for (i = 0; i <= n - 1; i++) scanf("%s", g + i);
  for (i = 0; i <= n - 1; i++)
    for (j = 0; j <= n - 1; j++)
      if (g[i][j] == '#') {
        int cnt = 1;
        for (k = 0; k <= 3; k++) {
          int rr = i + dx[k], cc = j + dy[k];
          if (rr >= 0 && rr < n && cc >= 0 && cc < n) {
            if (g[rr][cc] == '#') cnt++;
          }
        }
        if (cnt == 5) {
          g[i][j] = '.';
          for (k = 0; k <= 3; k++) {
            int rr = i + dx[k], cc = j + dy[k];
            if (rr >= 0 && rr < n && cc >= 0 && cc < n) {
              if (g[rr][cc] == '#') g[rr][cc] = '.';
            }
          }
        }
      }
  bool fl = 1;
  for (i = 0; i <= n - 1; i++)
    for (j = 0; j <= n - 1; j++)
      if (g[i][j] == '#') {
        fl = 0;
        goto getout;
      }
getout:
  if (fl)
    cout << "YES\n";
  else
    cout << "NO\n";
  return 0;
}
