#define _CRT_SECURE_NO_WARNINGS
#include "bits/stdc++.h"
using namespace std;
#define rep(i, n) for(int i=0; i<(n); ++i)
#define FOR(i, m, n) for(int i=(m); i<(n); ++i)
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(),(x).end()
#define mp make_pair
#define pb push_back
#define Cout(x) cout << (x) << endl
#define Cout2(x, y) cout << (x) << " " << (y) << endl
#define dump(x) cerr << #x << " = " << (x) << endl;
typedef long long LL;
typedef vector<int> VI;
typedef vector<LL> VL;
typedef vector<string> VS;
typedef vector<bool> VB;
typedef vector<vector<int>> VVI;
typedef pair<int, int> PII;
const int inf = 1e9;
const double pi = acos(-1.0);

int main() {
	int n;
	string s;
	cin >> n >> s;

	int ans = 0;
	FOR(diff, 1, (n - 1) / 2 + 1) {
		rep(be, n - diff * 2) {
			int i = be, j = be + diff, k = be + 2 * diff;
			ans += s[i] == 'U'&&s[j] == 'M'&&s[k] == 'G';
		}
	}
	Cout(ans);
}