#include <vector>
#include <string>
#include <iostream>
#include <iomanip>
#include <chrono>
#include <sstream>
#include <algorithm>
#include <numeric>

class muTimer
{
    using Clock = std::chrono::high_resolution_clock;
    bool active = false;
    Clock::duration   duration_;
    Clock::time_point start_ = Clock::now(), stop_ = Clock::now();

    muTimer(const muTimer&)             = delete;
    muTimer& operator=(const muTimer&)  = delete;
public:
    using ns       = std::chrono::nanoseconds;
    using mks      = std::chrono::microseconds;
    using ms       = std::chrono::milliseconds;
    muTimer() { reset(); start(); }
    ~muTimer() = default;
    muTimer& reset()
    {
        duration_ = std::chrono::nanoseconds(0);
        active    = false;
        return *this;
    }
    muTimer& start()
    {
        if (!active)
        {
            start_ = Clock::now();
            active = true;
        }
        return *this;
    }
    muTimer& stop()
    {
        if (active)
        {
            stop_      = Clock::now();
            duration_ += stop_ - start_;
            active     = false;
        }
        return *this;
    }
    template<typename T = mks>
        unsigned long long duration()
    {
        return static_cast<unsigned long long>
            (std::chrono::duration_cast<T>(stop_-start_).count());
    }
};


using namespace std;

const int Count = 1000000;

unsigned int Hovsepyan()
{
    unsigned int sum = 0;
    for(int n = 0; n < Count; ++n)
    {
        n = std::abs(n);
        if (n < 10) { sum += n; continue; }
        std::stringstream io;
        io << n;
        char t;
        while (io >> t)
            sum += t - '0';
    }
    return sum;
}

unsigned int olkhovich()
{
    unsigned int sum = 0;
    for(int n = 0; n < Count; ++n)
    {
        int number = n;
        while (number) {
            sum += number % 10;
            number /= 10;
        }
    }
    return sum;
}

unsigned int dIm0n()
{
    unsigned int sum = 0;
    for(int n = 0; n < Count; ++n)
    {
        const auto s = to_string(n);
        sum += accumulate(cbegin(s), cend(s), 0,
                          [](auto acc, auto x) {
                              return acc + (x - '0');});
    }
    return sum;
}

int main(int argc, const char * argv[])
{
    {
        muTimer mt;
        unsigned int s = Hovsepyan();
        mt.stop();
        cout << "Hovsepyan() == " << s << "  for " << mt.duration<>() << " mks\n";
    }
    {
        muTimer mt;
        unsigned int s = olkhovich();
        mt.stop();
        cout << "olkhovich() == " << s << "  for " << mt.duration<>() << " mks\n";
    }
    {
        muTimer mt;
        unsigned int s = dIm0n();
        mt.stop();
        cout << "dIm0n()     == " << s << "  for " << mt.duration<>() << " mks\n";
    }
}