#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

struct myStruct
{
	int num;
};

int main()
{
	vector<myStruct> numVec(20);
	int sum;

	for(int i = 0; i < 20; ++i)
		numVec[i].num = i+1;
	
	const size_t size = numVec.size();
	const size_t increment = 5;

for (size_t a = 0; a < size; ++a)
	{
	    size_t stop = a + std::min(size-a, increment);

	    sum = 0;
    	for (size_t b = a; b < stop; ++b)
	    {
    	    cout << "B: " << b << ", sum += " << numVec[b].num << endl;
        	sum += numVec[b].num;
	    }

    	cout << "Sum: " << sum << endl;
	}

	return 0;
}