#include <bits/stdc++.h>
using namespace std;
using lli = int_fast64_t;
using ulli = uint_fast64_t;
#define debug(x) cerr << #x << " : " << x << endl
#define debugv(x) cerr << #x << " : {";for(auto value_of_x:x){ cerr << value_of_x << ", ";}cerr << endl


namespace atcoder {
	template<typename T>
	T ncr(T left, T right) {
		right = min(left - right, right);
		T ans = 1;
		for (T i = 1; i <= right; i++) {
			ans = ans * (left - right + i) / i;
		}
		return ans;
	}

	const lli MOD = 1000000007;
	const lli LIMIT = 1'0'000'000'000'000'000 * 5;
	const int tenfive = 100000;
}

using namespace atcoder;

int main() {
	int N;
	string S;
	cin >> N;
	cin >> S;
	int ans = 0;
	for (int i = 0; i < N; i++) {
		if (S[i] == 'U') {
			for (int j = 1; i + 2 * j < N; j++) {
				if (S[i + j] == 'M'&&S[i + 2 * j] == 'G') {
					ans++;
				}
			}
		}
	}
	cout << ans << endl;
	return 0;
}