#include <bits/stdc++.h>
int a[111][111], v[111][111], n, sum = 0;
int judge(int x, int y) {
  if (a[x][y] && a[x - 1][y] && a[x + 1][y] && a[x][y - 1] && a[x][y + 1] &&
      !v[x][y])
    return 1;
  return 0;
}
int dfs(int x, int y) {
  int i, j;
  if (!sum) return 1;
  for (i = 1; i < n - 1; i++) {
    for (j = 1; j < n - 1; j++) {
      if (judge(i, j)) {
        a[i][j] = a[i - 1][j] = a[i + 1][j] = a[i][j - 1] = a[i][j + 1] = 0;
        sum -= 5;
        v[i][j] = 1;
        return dfs(i, j);
        a[i][j] = a[i - 1][j] = a[i + 1][j] = a[i][j - 1] = a[i][j + 1] = 1;
        sum += 5;
        v[i][j] = 0;
      }
    }
  }
}
int main() {
  int i, j, flag = 1;
  char ch;
  scanf("%d", &n);
  getchar();
  for (i = 0; i < n; i++) {
    for (j = 0; j < n; j++) {
      ch = getchar();
      v[i][j] = 0;
      sum += (a[i][j] = (ch == '#') ? 1 : 0);
    }
    getchar();
  }
  if (sum % 5)
    printf("NO\n");
  else {
    if (dfs(1, 1) == 1)
      printf("YES\n");
    else
      printf("NO\n");
  }
  return 0;
}
