/*
VIM: let b:cf5build="clang -std=c++20 -O2 -pthread -lstdc++ -I. {SRC} -o {OUT}"
VIM: let b:cf5run="{OUT}"
*/
#include <iostream>
#include <exception>
#include <chrono>
#include <vector>

void print(const std::vector<int>& row)
{
    for (auto i : row){
        std::cout << i << ',';
    }
    std::cout << std::endl;
}

void push(std::vector<int> row)
{
    print(row);
    auto q = row.begin();
    auto pe = row.end();
    for (auto p = row.begin()+1; p != pe; ++p){
        if (*p==0){
            continue;
        }
        else if (*q == 0){
            *q+=*p;
            *p = 0;
        }
        else if (*q == *p){
            *q+=*p;
            *p = 0;
            ++q;
        }
        else {
            *++q = *p;
            if (*q != *p){
                *p = 0;
            }
        }
    }
    print(row);
}

int main ( void )
{try{
    auto begin = std::chrono::high_resolution_clock::now();

    push({4, 0, 4, 8});

    //......

    auto end = std::chrono::high_resolution_clock::now();
    std::chrono::duration<double> seconds = end - begin;
    std::cout << "Time: " << seconds.count() << std::endl;
    return 0;
}
catch ( const std::exception& e )
{
    std::cerr << std::endl
            << "std::exception(\"" << e.what() << "\")." << std::endl;
    return 2;
}
catch ( ... )
{
    std::cerr  << std::endl
            << "unknown exception." << std::endl;
    return 1;
}}