#include<bits/stdc++.h>
using namespace std;
string s1,s2;
int main()
{
	int n,ans=0,maxx=-1;cin>>n;
	cin>>s1;
	for (int i=1;i<=n;++i) s2[i]=s1[i-1];
	for (int i=1;i<=n;++i)
	{
		ans=0;
		int left=i,right=i+1;
		while(left!=i+1&&(s2[left]==s2[i]||(s2[left]=='w')))
		{
			if (left==0) left=n;
			--left;
			++ans;
		}
		while (right!=i&&(s2[right]==s2[i+1]||s2[right]=='w'))
		{
			if (right==n) right=0;
			++right;
			++ans;
		}
		maxx=max(ans,maxx);
	}
	cout<<maxx;
	return 0;
}