import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int x = Integer.parseInt(br.readLine());
		int y = Integer.parseInt(br.readLine());
		int l = Integer.parseInt(br.readLine());
		int n=0;
		if(y<0)n=2;
		else if(x!=0)n=1;
		System.out.println((Math.abs(x)+l-1)/l+(Math.abs(y)+l-1)/l+n);
	}
}