#include <iostream>
    #include <valarray>
    
    int main() 
    {
    
    	std::valarray<int> a{2, 4, 8};
    	a = std::valarray<int>(a + a[0]);
    
    	for (auto n : a) 
    		std::cout << n << " ";
    
    	std::cout << std::endl << std::endl;
    
    	return 0;
    }