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