Finding second maximum using std::set, for_each, custom ordering

main.cpp

    auto cmp = [](int a, int b){return a > b;};
    set<int, decltype(cmp)> s(cmp);
    for_each(evens, evens + 100001, [&](int n){s.insert(n);});
    int num_secondpop_evens = 0;
    if(s.size() > 1){
      num_secondpop_evens = *(++s.begin());
    }