#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
using namespace std;
int main()
{
int n,ans;
char a[10001];
scanf("%d",&n);
gets(a);
for(int i;i==0;i++)
{
if(a[i]='[')
ans++;
if(a[i]='[')
ans--;
}
if(ans==0) printf("YES");
else printf("NO");
return 0;