#include<bits/stdc++.h>
using namespace std;
int main(){
    int X,Y,N;
    cin>>X>>Y>>N;
    int ans=0;
    if(Y<0)ans+=2;
    else if(X!=0)ans++;
    ans+=(abs(X)+N-1)/N;
    ans+=(abs(Y)+N-1)/N;
    cout<<ans<<endl;
}