#include<iostream>
using namespace std;
int main()
{
    int a,b,c,ans=0;
    cin >> a>>b>>c;
   
    if(b<0)ans+=2;
    else if(a)ans++;
    if(b<0)b=-b;
    if(a<0)a=-a;
    ans+=(a+c-1)/c+(b+c-1)/c;
    cout<<ans;

return 0;
}