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