tijie

#include<bits/stdc++.h>
using namespace std;
int n, ans;
string s;
int func(int x) {
    int cnt = 0;
    for (int i = x; i >= 0; i--) {
        if(s[i] == s[x] || s[i] == 'w') cnt++;
        else break;
    }
    for (int i = x + 1; i <= 3 * n; i++) {
        if(s[i] == s[x+1] || s[i] == 'w') cnt++;
        else break;
    }
    return cnt;
}
int main() {
    cin >> n >> s;
    s = s + s + s;
    for (int i = n + 1; i <= 2 * n; i++) {
        if(s[i] == 'w') {
            s[i] = 'r';
            ans = max(func(i), ans);
            s[i] = 'b';
            ans  = max(func(i), ans);
            s[i] = 'w';
        }
        ans = max(func(i), ans);
    }
    ans = min(ans, n);
    cout << ans;
    return 0;
}