#include <iostream>
#include <sstream>
#include <string>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <vector>
#include <array>
#include <map>
#include <memory>
#include <algorithm>
#include <utility>

namespace Util
{

std::vector<std::string> Split(const std::string& str, const char delim);
std::string Itos(const int value);
std::string Ftos(const double value);
int Stoi(const std::string& buf);
double Stof(const std::string& buf);
std::vector<int> ConvertInt(const std::vector<std::string>& buffers);
std::vector<double> ConvertDouble(const std::vector<std::string>& buffers);

}// namespace Util

struct Point
{
	int x;
	int y;
};

int main()
{
	// 入出力の速度向上
	std::cin.tie(0);
	std::ios::sync_with_stdio(false);

	std::string buf;
	std::vector<std::string> buffers;

	Point target;
	int step;
	Point agent;
	int processCount;

	buffers.resize(3);
	for(int count = 0; count < static_cast<int>(buffers.size()); ++count)
	{
		std::getline(std::cin, buffers[count]);
	}

	target.x = Util::Stoi(buffers[0]);
	target.y = Util::Stoi(buffers[1]);
	step = Util::Stoi(buffers[2]);

	agent.x = 0;
	agent.y = 0;

	processCount = 0;

	// ゴールが上
	if(agent.y < target.y)
	{
		if(agent.x != target.x)
		{
			processCount += 1;
		}
	}
	// ゴールのY座標が同じ
	else if(agent.y == target.y)
	{
		if(agent.x != target.x)
		{
			processCount += 1;
		}
	}
	// ゴールが下
	else
	{
		processCount += 2;
	}

	processCount += std::abs(agent.y - target.y) / step + (std::abs(agent.y - target.y) % step == 0 ? 0 : 1);
	processCount += std::abs(agent.x - target.x) / step + (std::abs(agent.x - target.x) % step == 0 ? 0 : 1);
	printf("%d\n", processCount);


	return 0;
}


namespace Util
{

std::vector<std::string> Split(const std::string& str, const char delim)
{
	std::istringstream iss(str);
	std::vector<std::string> ret;
	std::string tmp;

	while(std::getline(iss, tmp, delim))
	{
		ret.push_back(tmp);
	}

	return ret;
}

std::string Itos(const int value)
{
	std::ostringstream ostream;
	ostream << value;
	return ostream.str();
}

std::string Itof(const double value)
{
	std::ostringstream ostream;
	ostream << value;
	return ostream.str();
}

int Stoi(const std::string& buf)
{
	return std::atoi(buf.c_str());
}

double Stof(const std::string& buf)
{
	return std::atof(buf.c_str());
}

std::vector<int> ConvertInt(const std::vector<std::string>& buffers)
{
	std::vector<int> ret(buffers.size());

	for(int cur = 0; cur < static_cast<int>(ret.size()); ++cur)
	{
		ret[cur] = Stoi(buffers[cur]);
	}

	return ret;
}

std::vector<double> ConvertDouble(const std::vector<std::string>& buffers)
{
	std::vector<double> ret(buffers.size());

	for(int cur = 0; cur < static_cast<int>(ret.size()); ++cur)
	{
		ret[cur] = Stof(buffers[cur]);
	}

	return ret;
}

}// namespace Util