#include "bits/stdc++.h"

using namespace std;

using ll = long long;
using ld = long double;

const double PI = 3.1415926535897932384626433832795;

const int dx[] = { 0, 1, 0, -1 };
const int dy[] = { -1, 0, 1, 0 };

int gcd(int x, int y) { return y ? gcd(y, x % y) : abs(x); }
ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : abs(x); }
int lcm(int x, int y) { return x / gcd(x, y) * y; }
ll lcm(ll x, ll y) { return x / gcd(x, y) * y; }

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	int n;
	string s;
	cin >> n >> s;

	int ans = 0;
	for (int i = 0; i < n - 2; i++) {
		for (int j = i + 1; j < n - 1; j++) {
			int k = j - i + j;

			if (k < 0 || k >= n) {
				continue;
			}

			if (s[i] == 'U' && s[j] == 'M' && s[k] == 'G') {
				ans++;
			}
		}
	}
	
	cout << ans << endl;

	return 0;
}