#include <string>
#include <iostream>
unsigned addiere_gerade_ziffern(const std::string& str)
{
    unsigned sum(0);
    for(int i = 0; i < str.size() - 1; i += 2)
    {
        sum += static_cast<int>(str[i]-'0');
    }
    return sum;
}

unsigned addiere_ungerade_ziffern(const std::string& str)
{
    unsigned sum(0);
    for(int i = 1; i < str.size() - 1; i += 2)
    {
        sum += static_cast<int>(str[i]-'0');;
    }
    return sum;
}

int main()
{
    std::string str("4012700963109");
    std::cout << "addiere_gerade_ziffern: " << addiere_gerade_ziffern(str) << "\n";
    std::cout << "addiere_ungerade_ziffern * 3: " << addiere_ungerade_ziffern(str) * 3 << "\n";
    std::cout << "gesamtsumme: " << addiere_gerade_ziffern(str) +  addiere_ungerade_ziffern(str) * 3 << "\n";
}