#include<iostream>
#include<stdio.h>
#include<math.h>

using namespace std;

int main(){
    int x, y, l;
    cin>> x>> y>> l;

    int cnt = 0;
    if(y < 0){
        cnt++; //to south
        y = -y;
    }
    cnt += ceil((double)y/l);

    if(x!=0) cnt++; //to west OR to east
    if(x < 0) x = -x;
    cnt += ceil((double)x/l);

    cout<< cnt<< endl;
    return 0;
}