#include <iostream>


void do_post_increment()
{
	const unsigned legal_age = 21 ;
	unsigned age = 0 ;

	while( age++ < legal_age )
	{
		std::cout << "Your age is " << age << ".\n" ;
		std::cout << "You can't have a beer until you are " << legal_age << "!\n\n";
	}
}

void do_pre_increment()
{
	const unsigned legal_age = 21 ;
	unsigned age = 0 ;

	while( ++age < legal_age )
	{
		std::cout << "Your age is " << age << ".\n" ;
		std::cout << "You can't have a beer until you are " << legal_age << "!\n\n";
	}
}

int main()
{
	do_post_increment() ;
	std::cout << '\n' ;
	do_pre_increment() ;
}