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

using ll = long long; 

ll n;
string wines;

ll x = 0;

int main() {
    ios::sync_with_stdio(0); 
    cin.tie(0);

    cin >> n >> wines; 
    ll curr = 0; 
    for (int i = 0; i < n; i++) {
        if (wines[i] == 'W') {
            curr++; 
        }
    }

    for (int i = 1; i <= n; i++) {
        if (wines[i - 1] == 'W') {
            curr--; 
        }
        if (wines[i + n - 1] == 'W') {
            curr++;
        }

        x = max(x, curr); 
    }
    
    cout << x; 
}