/* name: 1129
 * author: 5ab
 * created at: 2023-12-22
 */
#include <iostream>
#include <algorithm>
#include <numeric>
using namespace std;

#define all(x) (x).begin(), (x).end()
#define ssz(x) (int((x).size()))

auto chmax = [](auto& x, auto y) { if (x < y) x = y; };
auto chmin = [](auto& x, auto y) { if (y < x) x = y; };

using ll = long long;
const int max_n = 2e5;

char s[max_n * 2 + 1];
int c[max_n * 2];

signed main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int n;
	
	cin >> n >> s;
	for (int i = 0; i < 2 * n; i++)
	{
		if (s[i] == 'W')
			c[i >= n ? i - n : i + n]++;
		else
			c[i]--;
	}
	partial_sum(c, c + 2 * n, c);
	nth_element(c, c + n, c + 2 * n);
	
	ll ans = 1ll * n * (n - 1);
	for (int i = 0; i < 2 * n; i++)
		ans -= abs(c[n] - c[i]);
	cout << ans / 2 << endl;
	
	return 0;
}
// started coding at: 12-22 11:35:16