#include<bits/stdc++.h>
using namespace std;

int main(){
  double x,y,l;
  cin>>x;
  cin>>y;
  cin>>l;
  int cnt=0;
  if(y<0)cnt+=2;
  if(y>=0&&x!=0)cnt++;
  cnt+=ceil(abs(x/l))+ceil(abs(y/l));
  cout<<cnt<<endl;
  return 0;
}