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