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

int main()
{
    int x, y, l;
    int time = 0;

    cin >> x >> y >> l;
    if(x != 0){
        time++;
    }
    time += ceil(fabs(x)/l);
    if(x != 0 || y != 0){
        time++;
    }
    time += ceil(fabs(y)/l);
    if(y > 0){
        time--;
    }
    cout << time << endl;

    return 0;
}