#include <bits/stdc++.h>
#include <atcoder/convolution>
using namespace std;
using ll = long long;
vector<ll> solve(const vector<ll>& A, const vector<ll>& B) {
	const int N = A.size();
	vector<ll> res(N + N - 1, 0);
	if(N <= 1) return res;

	const int M = N / 2;
	vector<ll> AL{A.begin(), A.begin() + M}, BL{B.begin(), B.begin() + M};
	vector<ll> AR{A.begin() + M, A.end()}, BR{B.begin() + M, B.end()};

	vector<ll> lft = solve(AL, BL);
	vector<ll> rgt = solve(AR, BR);

	vector<ll> cross = atcoder::convolution_ll(AL,BR);

	for(int k = 0; k < (int)lft.size(); k++) res[k] += lft[k];

	for(int k = 0; k < (int)cross.size(); k++) res[k + M] += cross[k];

	for(int k = 0; k < (int)rgt.size(); k++) res[k + M + M] += rgt[k];

	return res;
}
int main() {
	std::ios_base::sync_with_stdio(false);
	std::cin.tie(nullptr);
	int N;
	cin >> N;
	string S;
	cin >> S;
	vector<ll> A(N), B(N);
	for(int i = 0; i < N; i++) {
		if(S[i] == 'U') A[i] = 1;
		if(S[i] == 'G') B[i] = 1;
	}
	auto C = solve(A, B);
	int ans = 0;
	for(int i = 0; i < C.size(); i++) if(i % 2 == 0 && S[i/2] == 'M') ans += C[i];
	cout << ans << endl;
}