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