#include <cassert>
#include <string>
#include <string_view>

inline std::string StringFromHex(const std::string_view& input)
{
    assert((input.size() & 1) == 0);

    std::string result;
    result.reserve(input.size() / 2);
    for (size_t i = 0; i < input.size(); i += 2)
    {
        auto val = std::stoi(std::string(input.substr(i, 2)), 0, 16);
        result.push_back(val);
    }
    return result;
}