#include <iostream>
#include <string>

int main() {
    int N;
    std::string S;
    std::cin >> N >> S;

    int ans = 0;
    for (int k = 1; k <= N; ++k) {
        for (int i = 0; i + k * 2 < N; ++i) {
            if (S[i] == 'U' && S[i + k] == 'M' && S[i + k * 2] == 'G') ++ans;
        }
    }

    std::cout << ans << std::endl;
    return 0;
}