import java.util.*;

public class Yukicoder_48{
	public static void main(String[] args){
		Scanner stdIn = new Scanner(System.in);
		int X = stdIn.nextInt();
		int Y = stdIn.nextInt();
		int L = stdIn.nextInt();
		int count = 0;

		if(X==0 && Y==0){
			System.out.println("0");
		}
		else{
			if(X>0){
			count++;
			int x = X/L;
			count += x;
			X = X - x*L;
			if(X!=0){
				count++;
			}

			}
			else if(X<0){
				count++;
				X = (-1)*X;
				int x = X/L;
				count += x;
				X = X - x*L;
				if(X!=0){
					count++;
				}
			}

			if(Y>0){
				int y = Y/L;
				count += y;
				Y = Y - y*L;
				if(Y!=0){
					count++;
				}
			}
			else if(Y<0){
				if(X==0){
					count++;
				}
				count++;
				Y = (-1)*Y;
				int y = Y/L;
				count += y;
				Y = Y - y*L;
				if(Y!=0){
					count++;
				}
			}

			System.out.println(count);

		}

	}
}