USACO_BEADS_C++

#include <bits/stdc++.h>
using namespace std;

string coloredNecklace (string necklace) {
    char currentColor = necklace[0];
    int maxBeadCount = 0;
    for (int i = 0; i < necklace.size(); i++) {
        if (necklace[i] != currentColor && necklace[i] != 'w') {
            currentColor = necklace[i];
        }
        if (necklace[i] == 'w') {
            necklace[i] = currentColor;
        }
    }
    return necklace;
}

void maxBeadCount (string necklace, int &max) {
    int d = 1;
    for (int i = 0; i < necklace.size() - 1; i++) {
        while (i < necklace.size() && (necklace[i] == necklace[i + 1] || necklace[i] == 'w')) {
            d++;
            i++;
        }
        if (d > max) {
            max = d;
        }
        d = 1;
    }
}

int main () {
    freopen ("beads.in", "r", stdin);
    freopen ("beads.out", "w", stdout);
    int max = 0, n;
    string s;
    cin >> n >> s;
    s += s;
    maxBeadCount(coloredNecklace(s), max);
    reverse(s.begin(), s.end());
    maxBeadCount(coloredNecklace(s), max);
    if (max > n) {
        max /= 2;
    }
    cout << max << endl;
    return 0;
}