import java.util.Scanner;

class Test {
	public static int corner(int x, int y, int l) {
		if(x / l == 0) {
			if(y / l == 0) {
				return x / l + y / l;
			} else {
				return x / l + y / l + 1;
			}
		} else {
			if(y / l == 0) {
				return x / l + y / l + 1;
			} else {
				return x / l + y / l + 2;
			}
		}
	}

	public static void main(String[] args) throws Exception {
		Scanner in = new Scanner(System.in);
		int x = in.nextInt();
		int y = in.nextInt();
		int l = in.nextInt();

		int temp1 = x / l;
		int temp2 = y / l;
		int ans = 0;
		if(y >= 0) {
			if(x == 0) {
				ans = corner(x,y,l);
			} else {
				ans = corner(x,y,l) + 1;
			}
		} else if(y < 0) {
			ans = corner(x,y,l) + 2;
		}

		System.out.println(ans);
	}
}