up03-2 (iterators)

#include <vector>
#include <iostream>

void process(std::vector<int64_t> &a, int64_t border)
{
    auto additive = 0;
    for (auto &c:a) {
        if (c >= border) {
            additive++;
        }
    }

    a.resize(a.size() + additive);
    auto last = a.end() - additive;
    for (auto i = a.rbegin() + additive; i != a.rend(); i++) {
        if (*i >= border) {
            *last = *i;
            last++;
        }
    }
}