/*
    No.48 ロボットの操縦
    https://yukicoder.me/problems/no/48
*/
#include <bits/stdc++.h>
using namespace std;

int calc(double x, double l) {
    return ceil(abs(x) / l);
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);

    long int dist = 0;
    double x, y, l;
    cin >> x >> y >> l;

    if (x != 0 && y >= 0)
        dist += 1;
    else if (y < 0)
        dist += 2;

    dist += calc(x, l) + calc(y, l);

    cout << dist << endl;
}