#include<bits/stdc++.h>
using namespace std;
int main(){
    int x,y,n,c=0;
    cin>>x>>y>>n;
    x=abs(x);
    if(y>0){
        c+=(y-1)/n+1;
        if(x!=0){
            c++;
            c+=(x-1)/n+1;
        }
    }else{
        if(x!=0){
            c++;
            c+=(x-1)/n+1;
        }
        if(y!=0){
            if(x==0) c++;
            c++;
            c+=(abs(y)-1)/n+1;
        }
    }
    cout<<c<<endl;
}