#include <vector>
#include <iostream>
#include <string>
#include <sstream>
#include <algorithm>
#include <utility>
#include <map>
#include <cmath>

using namespace std;
typedef long long ll;
typedef pair<ll,ll> P;

int main(){
	int x,y,l;
	cin >> x >> y >> l;
	int ans = 0;
	if(y < 0)ans++;
	if(y)ans+=ceil(double(abs(y))/l);
	if(x)ans+=ceil(double(abs(x))/l)+1;
	
	cout << ans << endl;
}