/*
*************************************************************************
* $ Author : honeyslawyer   $
* $ Name   : shashank gupta $
*************************************************************************
*
* Copyright 2013 @ honeyslawyer and shashank gupta
*
************************************************************************/
#include<cstdio>
#include<iostream>
#include<cmath>
//#include<conio.h>
#include<cstring>
#include<ctype.h>
#include<algorithm>
#include<vector>
#include<stdlib.h>
#include<map>
#include<queue>
#include<stack>
#include<set>
#include<string>
#include<climits>

#define mod 1000000007
#define ll long long

using namespace std;
ll gcd(ll a,ll b) {if(b==0) return a; return gcd(b,a%b);}

ll power(ll b,ll exp,ll m)
 {ll ans=1;
  b%=m;
  while(exp)
   {if(exp&1)
     ans=(ans*b)%m;
    exp>>=1;
	b=(b*b)%m;
   }
  return ans;
 }
char a[400][400];
int main()
{
  int n;
  char b;
  scanf("%d",&n);
  scanf("%c",&b);
  
  for(int i=0;i<n;i++)
  gets(a[i]);
  
  for(int i=1;i<n-1;i++)
  {
        for(int j=1;j<n-1;j++)
        {
            if(a[i][j]=='#')
            {
                if(a[i-1][j]=='#'&&a[i+1][j]=='#'&&a[i][j-1]=='#'&&a[i][j+1]=='#')
                {
                    a[i][j]='.';
                    a[i-1][j]='.';
                     a[i+1][j]='.';
                      a[i][j-1]='.';
                       a[i][j+1]='.';
                    }
            }
        }
    }
  for(int i=0;i<n;i++)
  {
        for(int j=0;j<n;j++)
        {
            if(a[i][j]=='#')
            {
                printf("NO\n");
                return 0;
            }
        }
    }
  printf("YES\n");

//getch();
return 0;
/*checklist
1)getch() and conio.h removed.*/
}