#include <iostream>
#include <cstdlib>
using namespace std;

int main()
{
	int i {10};

	//Because i is non-const, you're allowed to do all of these:
	++i;
	--i;
	i++;
	i--;
	i = 20;
	i += 30;
	cin >> i;

	const int j {20};

	//Because j is const, you're not allowed to do any of these:
	++j;
	--j;
	j++;
	j--;
	j = 30;
	j += 40;
	cin >> j;
	return EXIT_SUCCESS;
}