#include <iostream>
#include<vector>
#include<algorithm>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef tree<long long, null_type, less<long long>, rb_tree_tag, tree_order_statistics_node_update> oset;
#define int long long
int32_t main() {
ios_base::sync_with_stdio(false); cin.tie(NULL);
int n; cin >> n;
string s; cin >> s;
vector<int> w, b;
for (int i = 0; i < (n + n); ++i)
if (s[i] == 'W')
w.push_back(i);
else
b.push_back(i);
int mx = 0;
for (int k = 0; k < n; ++k) {
int ans = 0;
vector<pair<int, int>> res, a;
for (int i = 0; i < n; ++i)
res.push_back({ w[i], b[(i + k) % n] });
for(int i = 0; i < n; ++i)
a.push_back({min(res[i].second, res[i].first), -1}),
a.push_back({max(res[i].second, res[i].first), min(res[i].second, res[i].first)});
oset s;
sort(a.begin(), a.end());
for(auto x: a) {
if(x.second == -1) s.insert(x.first);
else s.erase(x.second),
ans += (s.size() - s.order_of_key(x.second));
}
mx = max(ans, mx);
}
cout << mx;
}
