import java.util.Scanner;

public class Answer {
	public static void main(String str[]) {
        Scanner sc = new Scanner(System.in);
        double x = Double.valueOf(sc.nextLine());
        double y = Double.valueOf(sc.nextLine());
        double l = Double.valueOf(sc.nextLine());

        int operationNum = 0;
        if(y<0) {
        	operationNum += 2;
        } else if(x != 0) {
        	operationNum += 1;
        }

        operationNum += (int) Math.ceil(Math.abs(x/l));
        operationNum += (int) Math.ceil(Math.abs(y/l));
        System.out.println(operationNum);
	}
}