import java.io.*;
import java.util.*;
import java.math.*;

class Main48 {
	
	public static void out (Object out) {
		System.out.println(out);
	}
	
	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 turnCnt = y < 0 ? 2 : x == 0 ? 0 : 1;
		x = Math.abs(x);
		y = Math.abs(y);
		int move1 = (double)x / l == x / l ? x / l : x / l + 1;
		int move2 = (double)y / l == y / l ? y / l : y / l + 1;
		
		out(move1 + move2 + turnCnt);
	}
}