#include <iostream>

int main() {
    int n;
    std::string s;
    std::cin >> n >> s;
    int ans = 0;
    for (int i = 0; i < n; i++) {
        for (int p = i+1; p < n; p++) {
            if (s[i] == 'U' && s[p] == 'M' && s[p + (p - i)] == 'G')
                ans++;
            }
    }
    std::cout << ans << std::endl;
    return 0;
}