#include <bits/stdc++.h>
using namespace std;
int gi() {
	int res = 0, w = 1;
	char ch = getchar();
	while (ch != '-' && !isdigit(ch)) ch = getchar();
	if (ch == '-') w = -1, ch = getchar();
	while (isdigit(ch)) res = res * 10 + ch - '0', ch = getchar();
	return res * w;
}
#define fi first
#define se second
#define pii pair<int, int>
using LL = long long;
using db = long double;
const int Mod = 998244353;
const int MAX_N = 2e6 + 5;
int N, s[MAX_N];
char str[MAX_N];
void solve() {
	scanf("%d %s", &N, str + 1);
	for (int i = 1; i < 2 * N; i++)
		s[i] = s[i - 1] + (str[i] == 'W');
	int mx = 0;
	for (int i = N; i < 2 * N; i++)
		mx = max(mx, s[i] - s[i - N]);
	printf("%d\n", mx);
}
int main () {
#ifndef ONLINE_JUDGE
    freopen("cpp.in", "r", stdin);
	//freopen("cpp.out", "w", stdout);
#endif
	int T = 1; //T = gi();
	while (T--) {
		solve();
	}
    return 0;
}