#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int (i)=(0);(i)<(int)(n);++(i))
using ll = long long;
using P = pair<int, int>;
using namespace std;

int main() {
    int X, Y, L;
    cin >> X >> Y >> L;
    int ans = 0;

    if (Y >= 0) {
        ans += (Y + L - 1) / L;
        if (X != 0) ans++;
        X = abs(X);
        ans += (X + L - 1) / L;
    }
    else {
        ans += 2;
        X = abs(X);
        ans += (X + L - 1) / L;
        Y = abs(Y);
        ans += (Y + L - 1) / L;
    }

    cout << ans << endl;
}