#include <iostream>
#include <cmath>

using namespace std;

int walkcount(int a, int b) {
    if ((a % b) == 0) {
        return (static_cast<int>(abs(a)) / b);
    } else {
        return (static_cast<int>(abs(a)) / b + 1);
    }
}

int main() {
    int x, y, l;
    cin >> x >> y >> l;

    int ans = 0;

    if (y == 0) {
            if (x != 0) {
            ans = walkcount(x, l);
            ans++;
        }
    } else if (0 < y) {
        if (x == 0) {
            ans = walkcount(y, l);
        } else if (x != 0) {
            ans = walkcount(y, l) + walkcount(x, l);
            ans++;
        }
    } else if (y < 0) {
        if (x == 0) {
            ans = walkcount(y, l);
            ans += 2;
        } else if (x != 0) {
            ans = walkcount(y, l) + walkcount(x, l);
            ans += 2;
        }
    }
    cout << ans <<endl;
    return 0;
}