/*
ID: bradyawn
PROG: beads
LANG: C++11
*/
#include <iostream>
#include <fstream>
#include <string>
#include <vector>

using namespace std;

int mod(int x, int y)
{
    while (x < 0)
    {
        x += y;
    }
    return (x % y);
}

int findLen(string &neck, int index, int N) //BOTHWARDS!!!111!!!
{
    int forNum;
    int backNum;
    char color = 'w';
    int i = index;
    //Count Forwards
    for (forNum = 0; forNum < N; forNum++ )
    {
        i = mod(index+forNum, N);
        if (color == 'w' && neck[i] != 'w')
            color = neck[i];

        if((color != 'w')&&(color != neck[i])&&(neck[i] != 'w'))
            break;
    }

    //Backwards
    color = 'w';
    i = mod(index-1, N);
    for (backNum = 0; backNum < N; backNum++)
    {
        i = mod(index-1-backNum, N);
        if (color == 'w' && neck[i] != 'w')
            color = neck[i];

        if((color != 'w')&&(color != neck[i])&&(neck[i] != 'w'))
            break;
    }

    int numBeads = forNum + backNum;
    if (numBeads > N) numBeads = N;
    return numBeads;
}

int main ()
{

    ifstream inf("beads.in");
    ofstream outf("beads.out");
    // Solution

    //Gathering Input
    int N; //amount of beads
    string neck; //necklace sequence
    int max = 2;

    inf >> N;
    inf >> neck;


    for (int i = 0; i < N; i++) //brute force
    {
        int cur = findLen(neck, i, N);
        if (cur > max) max = cur;
    }


    outf << max << endl;

    // End of Solution
    inf.close();
    outf.close();
}