#include <vector>
#include <iostream>
#include <cstdint>
#include <algorithm>

class Accum {
    public:
        int sum;
        Accum(int s) {
            sum = s;
        }

        void operator() (int &value) {
            sum += value;
            std::cout << sum << std::endl;
        }
};

int main()
{
    std::vector <int> v{1, 2, 3, 4, 5};

    Accum inst(0);
    std::for_each(v.begin(), v.end(), inst);
    std::cout << inst.sum << std::endl;
}