#include<bits/stdc++.h>
using namespace std;
int n,ans;
string s;
int main(){
	cin>>n>>s;
	for(int pos=0;pos<n;pos++){
		int i=pos+1,j=pos,cnt=0;
		if(pos==n-1)i=0;
		while(s[i]==s[pos+1]||s[i]=='w'){
			i++,cnt++;
			if(i==n)i=0;
		}
		while(s[j]==s[pos]||s[j]=='w'){
			j--,cnt++;
			if(j==-1)j=n-1;
		}
		ans=max(ans,cnt);
	}
	cout<<ans;
	return 0;
}