#include <iostream>
#include <cmath>

using namespace std;

int main(int argc, char const* argv[]) {
    int x[2], l, ans = 0;

    cin >> x[0] >> x[1] >> l;

    if (x[1] < 0) {
        ans += 2;
    } else if (x[0] != 0) {
        ans += 1;
    }

    for (int i = 0; i < 2; i++) {
        if (abs(x[i]) % l == 0) {
            ans += abs(x[i]) / l;
        } else {
            ans += abs(x[i]) / l + 1;
        }
    }

    cout << ans << endl;
    return 0;
}