//No.48 ロボットの操縦

import java.util.*;
import java.io.*;
import static java.util.Arrays.*;
import static java.lang.Math.*;

public class No48 {
    
    static final Scanner sc = new Scanner(System.in);
    static final PrintWriter out = new PrintWriter(System.out,false);

    static void solve() {
        int x = sc.nextInt();
        int y = sc.nextInt();
        int l = sc.nextInt();
        int ans = (x == 0 && y >= 0 ? 0 : (y >= 0 ? 1 : 2));
        x = abs(x); y = abs(y);
        ans += x/l + (x%l == 0 ? 0 : 1) + y/l + (y%l == 0 ? 0 : 1); 
        out.println(ans);
    }

    public static void main(String[] args) {
        long start = System.currentTimeMillis();

        solve();
        out.flush();

        long end = System.currentTimeMillis();
        //trace(end-start + "ms");
        sc.close();
    }

    static void trace(Object... o) { System.out.println(deepToString(o));}
}