#include <bits/stdc++.h>
using namespace std::literals::string_literals;
using i64 = long long;
using std::cout;
using std::endl;
using std::cin;

int main() {
	int n; scanf("%d", &n);
	std::string s; cin >> s;
	
	int ans = 0;
	for(int i = 0; i < n; i++) {
		for(int j = i + 1; j < n; j++) {
			int k = 2 * j - i;
			if(k <= j or k < 0 or k >= n) continue;
			
			ans += (s[i] == 'U' and s[j] == 'M' and s[k] == 'G');
		}
	}
	
	printf("%d\n", ans);
	return 0;
}