#include <bits/stdc++.h>
#define mp make_pair
#define all(vec) vec.begin(), vec.end()
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
const ll INF = 1LL << 30;
const ll LINF = 1LL << 60;
const double eps = 1e-9;
const ll MOD = 1000000007LL;
int main() {
    int n;
    cin >> n;
    string s;
    cin >> s;
    int ans = 0;
    for(int i = 0; i < n; i++) {
        if(s[i] != 'U') continue;
        for(int j = i + 2; j < n; j++) {
            if(s[j] != 'G') continue;
            if((j - i) % 2) continue;
            if(s[i + (j - i) / 2] == 'M') ans++;
        }
    }
    cout << ans << endl;
}