#include <iostream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <queue>

#include <map>
#include <set>
#include <string>
#include <algorithm>
#include <functional>
using namespace std;
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define INF 1<<30
#define MP make_pair
#define mp make_pair
#define pb push_back
#define PB push_back
#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define ll long long
#define ull unsigned long long

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    double x, y, l;
    cin >> x >> y >> l;

    int res = 0;
    if(y >= 0 && x == 0) {
        res = ceil(y/l);
    } else if(y >= 0 && x != 0) {
        res = ceil(y/l) + ceil(abs(x)/l) + 1;
    } else {
        res = ceil(-y/l) + ceil(abs(x)/l) + 2;
    }

    cout << res << endl;
    return 0;
}