#include<bits/stdc++.h>
#define int long long
using namespace std;
int n , ans , sum;
string s;
signed main() {
	cin >> n >> s;
	s += s;
	for (int i = 0;i < n;i ++) {
		sum = 0; char c = s[i];
		if (c == 'w') continue;
		int z;
		for (z = i;s[z] == c || s[z] == 'w';z ++) {
			sum ++;
		}
		z = i + n - 1;
		for (;s[z] == 'w';z --) sum ++;
		c = s[z];
		for (;s[z] == 'w' || s[z] == c;z --) {
			sum ++;
		}
		ans = max (ans , sum);
	}
	cout << min (ans , n);
	return 0;
}

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