#include <iostream>
#include <string>
#include <vector>
 
using std::string; using std::vector; using std::cout; using std::cin; using std::endl;
 
int main ()
{
    vector<unsigned> numbers {5, 6, 7, 8, 9, 10};
 
    auto count = numbers.size();
 
	std::cout << " adjacent pair: " << std::endl;
    for (auto i = 0; i < numbers.size()-1; i++)
	{
        std::cout << (numbers[i] + numbers[i+1]) << "\t";
    }
	std::cout << std::endl;
 
	std::cout << " head-tail pair: " << std::endl;
	for (auto i = 0; i < count/2; ++i) 
	{       
      std::cout << (numbers[i] + numbers[count - i -1]) << "\t"; 	  
    }
	std::cout << std::endl;
 
	return 0;
}

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