#include <bits/stdc++.h>
using namespace std;

int main() {
	int X,Y,L,count=0;
	cin>>X>>Y>>L;
	if(Y<0) count+=2;
	else if(X)	count++;

	if(X<0)		X=-X;
	count+=ceil((double) X/L);

	if(Y<0)		Y=-Y;
	count+=ceil((double) Y/L);
	
	cout<<count<<endl;
	return 0;
}