#include<iostream>
#include<algorithm>
using namespace std;
using lint=int64_t;

int main()
{
	int X,Y,L;

	cin >> X >> Y >> L;

	int ans=0;
	if(X!=0)ans++;
	if(Y<0)ans++;
	ans+=(abs(X)+L-1)/L;
	ans+=(abs(Y)+L-1)/L;

	cout << ans << endl;
	return 0;
}