#include<iostream>
#include<cstdlib>
using namespace std;

int main(){
  int X,Y,L;
  cin>>X>>Y>>L;
  int cnt = 0;
  cnt += (abs(Y)+L-1)/L;
  cnt += (abs(X)+L-1)/L;
  if(Y >= 0){
    if(X != 0) cnt++;
  }else{
    cnt += 2;
  }
  cout<<cnt<<endl;
  return 0;
}