#include <iostream>
#include <vector>
#include <functional>
#include <chrono>
#include <random>
#include <map>

using namespace std;

const int N = 2e6 + 3;

int n, prefix[N], a[N];
string s;

int get_sum(int l, int r){
    if(l > r) return 0;
    return prefix[r] - prefix[l - 1];
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(NULL);

    cin >> n >> s;
    // cin >> n;
    mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
    for(int i = 1; i <= 2 * n - 1; ++i){
        a[i] = s[i - 1] == 'W';
        // a[i] = 1;
        prefix[i] = prefix[i - 1] + a[i];
    }
   
    int ans = 0;
    for(int i = 1; i <= n; ++i)
    ans = max(ans, get_sum(i, i + n - 1));

    cout << ans << "\n";
}