```go
package main

import (
	"bufio"
	"fmt"
	"os"
)

func main() {
	in := bufio.NewReader(os.Stdin)
	var n int
	fmt.Fscan(in, &n)
	g := make([][]byte, n)
	for i := 0; i < n; i++ {
		var s string
		fmt.Fscan(in, &s)
		g[i] = []byte(s)
	}

	for i := 1; i <= n-2; i++ {
		for j := 1; j <= n-2; j++ {
			if g[i][j] == '#' && g[i-1][j] == '#' && g[i+1][j] == '#' && g[i][j-1] == '#' && g[i][j+1] == '#' {
				g[i][j] = '.'
				g[i-1][j] = '.'
				g[i+1][j] = '.'
				g[i][j-1] = '.'
				g[i][j+1] = '.'
			}
		}
	}

	for i := 0; i < n; i++ {
		for j := 0; j < n; j++ {
			if g[i][j] == '#' {
				fmt.Print("NO")
				return
			}
		}
	}
	fmt.Print("YES")
}
```