import java.util.Scanner;

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

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

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