#include <string>
#include <iostream>
using namespace std;
int main() {
	int N; string S;
	cin >> N >> S;
	int cnt = 0;
	for (int i = 2; i <= N; i += 2) {
		for (int j = 0; j <= N - i; ++j) {
			if (S[j] == 'U' && S[j + i / 2] == 'M' && S[j + i] == 'G') {
				++cnt;
			}
		}
	}
	cout << cnt << endl;
	return 0;
}