M

#include<iostream>
#include <iomanip>
int main()
{
    int count;
    std::cin>>count;
    count=abs(count);
    double* massive=new double[count];
    for (int index{1}; index<=count; ++index) {
        std::cin>>massive[index];
    }
    int times{0};
    double sum{0};
    for (int index{3}; index<count; index+=3) {if(massive[index]>0){sum+=massive[index];++times;}}
    std::cout<<times<<" "<<std::setprecision(3)<<sum;
}