#include <iostream>
using namespace std;

int main() {
    int X, Y, L;
    cin >> X;
    cin >> Y;
    cin >> L;

    if (Y < 0) {
        cout << 1 + (abs(X) + L - 1) / L + 1 + (abs(Y) + L - 1) / L << endl;
    } else {
        if (X)
            cout << (abs(Y) + L - 1) / L + 1 + (abs(X) + L - 1) / L << endl;
        else
            cout << (abs(Y) + L - 1) / L << endl;
    }
}