#include <iostream>
#include <cstdio>
#include <vector>
#include <map>
#include <queue>
#include <string>
#include <algorithm>

#define REP(i, n) for(ll i = 0; i < (n); i++)
#define INF 1e16
#define MOD 1e9 + 7

using namespace std;
using ll = long long;



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