#include <bits/stdc++.h>
#define MULTI int _; cin >> _; while(_--)
#define fi first
#define se second
#define pb(a) push_back(a)
#define rep(i, n) for(int i = 0; i < n; i++)
#define reps(i, n, m) for(int i = n; i <= m; i++)
#define repsv(i, n, m) for(int i = n; i >= m; i--)
#define vsz(a) (int)(a.size())
#define mp(a, b) make_pair(a, b)
#define all(a) a.begin(), a.end()

using namespace std;

typedef pair<double, double> pdd;
typedef pair<int, int> pii;
typedef vector<bool> vb;
typedef vector<int> vi;
typedef long long int ll;
typedef long double ld;
typedef vector<ll> vll;

#ifdef LOCAL
#include "debugs.hpp"
#else
#define dbg(...) 0
#endif


void solve(){
    int n;
    string s;
    cin >> n >> s;
    vi v(2*n-1);
    rep(i, 2*n-1)
        v[i] = (s[i] == 'W' ? 1 : 0);
    int sum = 0;
    int r = 0, res = 0, l = 0;
    rep(i, n) sum += v[r++];
    res = sum;
    rep(i, n-1){
        sum -= v[l++];
        sum += v[r++];
        res = max(res, sum);
    }
    cout << res << '\n';
}

int main(){
    ios_base::sync_with_stdio(false);
    // MULTI
    solve();
}