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

int main() {

double a,b,c;
int count =0;
cin>>a>>b>>c;
if(a!=0&&b>=0){count+=1;}
if(b<0){count+=2;}

count+=ceil(abs(a)/c)+ceil(abs(b)/c);
cout<<count<<endl;
}