#include <bits/stdc++.h>

#define fi first
#define se second
#define forn(i, n) for (int i = 0; i < (int)n; ++i)
#define for1(i, n) for (int i = 1; i <= (int)n; ++i)
#define fore(i, l, r) for (int i = (int)l; i <= (int)r; ++i)
#define ford(i, n) for (int i = (int)(n)-1; i >= 0; --i)
#define fored(i, l, r) for (int i = (int)r; i >= (int)l; --i)
#define pb push_back
#define el '\n'
#define db(x) cout << #x << " " << x << el
#define ri(n) scanf("%d", &n)
#define sz(v) ((int)v.size())
#define all(v) v.begin(), v.end()
#define allr(v) v.rbegin(), v.rend()

using namespace std;

typedef long long ll;
typedef double ld;
typedef pair<int, int> ii;
typedef pair<char, int> pci;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;

const int inf = 1e9;
const int nax = 1e5 + 200;
const ld pi = acos(-1);
const ld eps = 1e-9;

int dr[] = {1, -1, 0, 0, 1, -1, -1, 1};
int dc[] = {0, 0, 1, -1, 1, 1, -1, -1};

void sol(){
    int n;
    cin >> n;
    string s;
    cin >> s;
    int N = 2*n - 1;
    int l = 0, r = 0;
    int cnt = 0;
    while(r < n){
        if(s[r] == 'W')++cnt;
        ++r;
    }
    int ans = cnt;
    while(r < N){
        if(s[r] == 'W')++cnt;
        if(s[l] == 'W')--cnt;
        ans = max(ans, cnt);
        ++r;
        ++l;
    }
    cout << ans << el;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cout << setprecision(20) << fixed;
    int t = 1;
    // cin >> t;
    while(t--)sol();
}