// No.48 ロボットの操縦
#include <iostream>
using namespace std;

int main() {
    int X, Y, L;
    cin >> X >> Y >> L;
    if (Y > 0) {
        if (X != 0) cout << (abs(X) + L - 1) / L + (Y + L - 1) /  L + 1 << endl; 
        else cout << (Y + L - 1) / L << endl;
    } else if (Y < 0) {
        if (X != 0) cout << (abs(X) + L - 1) / L + (-Y + L - 1) / L + 2 << endl;
        else cout << (-Y + L - 1) / L + 1 << endl;
    } else {
        if (X != 0) cout << (abs(X) + L - 1) / L + 1 << endl;
        else cout << 0 << endl;
    }
}