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

template<typename T>
void fin(T a){
  cout<<a<<endl;
  exit(0);
}

signed main(){
    int x,y,l;cin>>x>>y>>l;
    int ans=0;
    if(y>=0&&x)ans+=1;
    if(y<0)ans+=2;
    x=abs(x);
    y=abs(y);
    if(x)ans+=(x-1)/l+1;
    if(y)ans+=(y-1)/l+1;
    cout<<ans<<endl;
}