#include 
std::begin        | returns an iterator to the beginning of a container 
std::end        | returns an iterator to the end of a container 
std::size        | returns the length of string
std::to_string    | converts a number to string
std::stoi        | converts a string to a signed integer
std::getline     | read data from an I/O stream into a string
std::swap          | specializes the std::swap algorithm
std::empty         | checks whether the container is empty