#include<cstdio>
using namespace std;
int n,ans=0;
char a[10005];
int main (){
    scanf ("%d",&n);
    scanf ("%s",a+1);
    for (int i=1;i<=n;i++) a[i+n]=a[i],a[i+2*n]=a[i];
	for (int i=n+1;i<=2*n;i++){
		int s=0;
		for (int j=i-1;j>=i-n;j--){
			if (a[i-1]==a[j]||a[j]=='w') s++;
			else break;
		}
		for (int j=i;j<=i+n;j++){
			if (a[i]==a[j]||a[j]=='w') s++;
			else break;
		}
		if (s>ans) ans=s;
	}
	if (ans>n) ans=n;
	printf ("%d",ans);
	return 0;
}