#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;

int main() {
    int n; cin >> n;
    string s; cin >> s;
    int cnt = 0;
    for (int i = 0; i < n; i++) if (s[i] == 'M') {
        int rng = min(i, n - i - 1);
        for (int k = 1; k <= rng; k++) {
            if (s[i - k] == 'U' && s[i + k] == 'G') cnt++;
        }
    }
    cout << cnt << endl;
    return 0;
}