#include <iostream>

void swap(int &a, int &b)
{
    int tmp = a;
    a = b;
    b = tmp;
}

int main()
{
	int a = 10;
	int b = 20;
	
	std::cout<< "[a, b]: ["<< a<< ", "<< b<< "]\n";
	
	swap(a, b);
	
	std::cout<< "[a, b]: ["<< a<< ", "<< b<< "]\n";
	return 0;
}