import java.util.Scanner;

public class No48 {
	public static void main(String[]args) {
		Scanner sc =new Scanner(System.in);

		int X,Y,L,cnt;
		X = sc.nextInt();
		Y = sc.nextInt();
		L = sc.nextInt();
		cnt=0;

		if(Y>=0) {
			while(Y>0) {
				Y=Y-L;
				cnt++;
			}
			if(X>0) {
				cnt++;
				while(X>0) {
					X=X-L;
					cnt++;
				}
			}
			else if(X<0){
				cnt++;
				X=(-1)*X;
				while(X>0) {
					X=X-L;
					cnt++;
				}
			}
		}
		else {
			Y=(-1)*Y;
			while(Y>0) {
			Y=Y-L;
			cnt++;
		}
			if(X>0) {
				cnt+=2;
				while(X>0) {
					X=X-L;
					cnt++;
				}
			}
			else {
				cnt+=2;
				X=(-1)*X;
				while(X>0) {
					X=X-L;
					cnt++;
				}
			}
		}

		System.out.println(cnt);


	}

}