#include <bits/stdc++.h>
#define rep(i,n) for(long long i=0;i<(n);++i)
using namespace std;
typedef long long ll;

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	int n;
	cin >> n;
	string S;
	cin >> S;
	ll ans = 0;
	for (int i = 0; i < n; ++i) {
		if (S[i] == 'M') {
			int k = min(i + 1, n - i);
			for (int j = 0; j < k; ++j) {
				if (S[i - j] == 'U' && S[i + j] == 'G') {
					ans++;
				}
			}
		}
	}
	cout << ans << endl;
	return 0;
}