import java.util.Scanner;

public class No48 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int X = sc.nextInt();
        int Y = sc.nextInt();
        int L = sc.nextInt();
        int ans = 0;

        ans += (Math.abs(Y) + L - 1) / L;
        ans += (Math.abs(X) + L - 1) / L;
        if(Y < 0){
            ans++;
        }
        if(X != 0){
            ans++;
        }

        System.out.println(ans);
    }
}