#include <bits/stdc++.h>

#define show(x) cout << #x << " = " << x << endl

using namespace std;
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;

template <typename T>
ostream& operator<<(ostream& os, const vector<T>& v)
{
    os << "sz=" << v.size() << "\n[";
    for (const auto& p : v) {
        os << p << ",";
    }
    os << "]\n";
    return os;
}

template <typename S, typename T>
ostream& operator<<(ostream& os, const pair<S, T>& p)
{
    os << "(" << p.first << "," << p.second
       << ")";
    return os;
}


constexpr ll MOD = 1e9 + 7;

template <typename T>
constexpr T INF = numeric_limits<T>::max() / 100;

int main()
{
    int x;
    int y;
    int l;
    cin >> x >> y >> l;
    if (x == 0 and y >= 0) {
        cout << (y - l + 1) / l << endl;
        return 0;
    }
    int round = 0;
    if (y < 0) {
        round = 2;
    } else {
        round = 1;
    }
    cout << round + (abs(x) + l - 1) / l + (abs(y) + l - 1) / l << endl;
    return 0;
}