#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
using ll = long long;

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

    int n;
    cin >> n;

    string s;
    cin >> s;

    int r = 0;
    for (int i = 0; i < n; i++) {
        if (s[i] == 'M') {
            int m = min(i, n - 1 - i);
            for (int h = 1; h <= m; h++) {
                if (s[i - h] == 'U' && s[i + h] == 'G') r++;
            }
        }
    }

    cout << r << endl;

    return 0;
}