#include <fstream>
#include <iostream>
#include <string>


int main() {

	//std::ifstream inf("Text.txt");	std::cin.rdbuf(inf.rdbuf());

	int N;
	std::cin >> N;

	std::string S;
	std::cin >> S;

	int ans = 0;

	for (int i = 0; i < N; i++) {
		if (S[i] == 'U') {
			for (int j = i + 1; j < N; j++) {
				if (S[j] == 'M') {
					if (j + j - i < N) {
						if (S[j + j - i] == 'G') {
							ans++;
						}
					}
				}
			}
		}
	}

	std::cout << ans << std::endl;
	
	return 0;

}