#include <iostream>
#include <string>
#include <algorithm>
#include <cctype>
#include <cmath>
using namespace std;

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

    cout << (int)(ceil((double) X/L) + ceil((double) Y/L) + cnt) <<endl;
}