#include<bits/stdc++.h>
using namespace std;
int main(){
 int x,y,l;
 cin>>x>>y>>l;
 int ans=0;
 if(x==0){
  ans+=abs(y/l);
  if(y%l!=0)ans++;
  if(y<0)ans+=2;
 }else{
  ans+=abs(y/l);
  if(y%l!=0)ans++;
  ans+=abs(x/l);
  if(x%l!=0)ans++;
  ans++;
  if(y<0)ans++;
 }


 cout<<ans<<endl;
 return 0;
}