#include <iostream>
#include <vector>

int main() {
	std::vector<int> vecA = { 1, 2, 3 };
	std::vector<int> vecB = { 1, 2, 3, 4, 5, 6, 7 };
	
	for (auto a = vecA.begin(), b = vecB.begin(); b != vecB.end(); ++a, ++b)
	{
		if (a == vecA.end())
			a = vecA.begin();
			
		std::cout << "a=" << *a << ", b=" << *b << std::endl;
	}
	
	return 0;
}