import java.util.Scanner;


public class Main_yukicoder48 {

    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 ret = 0;
        if (x == 0 && y == 0) {
        } else if (x == 0 && y > 0) {
        	ret = (y + l - 1) / l;
        } else if (x == 0 && y < 0) {
        	ret = 2;
        	ret += (Math.abs(y) + l - 1) / l;
        } else if (x != 0 && y == 0) {
        	ret = 1;
        	ret += (Math.abs(x) + l - 1) / l;
        } else if (x != 0 && y > 0) {
        	ret = 1;
        	ret += (Math.abs(y) + l - 1) / l;
        	ret += (Math.abs(x) + l - 1) / l;
        } else {
        	ret = 2;
        	ret += (Math.abs(y) + l - 1) / l;
        	ret += (Math.abs(x) + l - 1) / l;
        }

        System.out.println(ret);
        
        sc.close();
    }
}