#include <iostream>
#include <cmath>

int main()
{
	double accuracyLimit = 0;
	std::cout << "Enter range accuracy limit: " << std::endl;
    std::cin >> accuracyLimit;
   	std::cout << "Accuracy limit = " << accuracyLimit << std::endl;
    
	double sum = 0;
	double item = 0;
	double i = 1;
	
	do
	{
		auto numerator = std::pow(-1, i);
		auto denominator = i  * (i  + 1) * (i + 2);
		item =  numerator / denominator;
		std::cout 
			<< "i=" << i 
			<< " item=" <<  item << " (" << numerator << "/" << denominator << ")" 
			<< std::endl;
		sum += item;
		++i;
	}
	while (std::abs(item) > accuracyLimit);

    std::cout << std::endl << " === Calculating finished " << std::endl;
    std::cout << "Range items count = " << --i << std::endl;
    std::cout << "Range amount = " << sum << std::endl;
}