#include<iostream>

int main() {
	int x, y, l, count = 0;
	std::cin >> x >> y >> l;

	if(y != 0){
		count += abs(y) / l + 1;
		if (y%l == 0)count--;
		if (y < 0)count += 2;
	}

	if (x != 0) {
		count++;//左か右への回転
		count += abs(x) / l + 1;
		if (x%l == 0)count--;
		if (y < 0)count--;
	}

	std::cout << count << std::endl;
	return 0;
}