#include <iostream>
#include <string>

using namespace std;

int n;
string s;

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