#include "bits/stdc++.h"

using namespace std;

#define int long long
#define ll long long
typedef pair<int, int> P;
#define mod 1000000007
#define INF (1LL<<60)

#define rep(i,n) for(int i=0, i##_len=(n); i<i##_len; ++i)
#define YES cout << "YES" << endl;
#define Yes cout << "Yes" << endl;
#define NO cout << "NO" << endl;
#define No cout << "No" << endl;


signed main(){

	int N;
	string s;
	cin >> N >> s;
	int ans = 0;
	for (int i = 1; i <= N - 2; i++){
		for (int j = i + 1; j <= N - 1; j++){
			int k = 2 * j - i;
			if (k<1 || k> N) continue;

			if (s[i - 1] == 'U' && s[j - 1] == 'M' && s[k - 1] == 'G')
				ans++;
		}
	}

	cout << ans << endl;
	return 0;
}