#include <iostream>
#include <string>
using namespace std;

int n;
string s;

int main() {
	int i, j;
	int ans = 0;
	
	cin >> n >> s;
	for (i = 0; i < n; i++) {
		for (j = i + 1; j < n; j++) {
			int k = j + (j - i);
			if (k >= n) continue;
			if (s[i] == 'U' && s[j] == 'M' && s[k] == 'G') ans++;
		}
	}
	cout << ans << endl;
	return 0;
}