Something like this should be fine, typing on mobile so excuse any syntax errors.
std::vector user_inputs;
while (user_inputs.size() < 5)
{
int user_arg = 0;
std::cout << "Please enter number " << (user_inputs.size() + 1) << ": ";
std::cin >> user_arg;
user_inputs.push_back(user_arg);
}
std::sort(user_inputs.begin(), user_inputs.end());
std::cout << "Lowest value entered:" << user_inputs.front() << std::endl;
std::cout << "Highest value entered:" << user_inputs.back() << std::endl;