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

public class Main {
	public static void main(String[] args) {
		BufferedReader buff = new BufferedReader(new InputStreamReader(System.in));

		try {
			int X = Integer.parseInt(buff.readLine());
			int Y = Integer.parseInt(buff.readLine());
			int L = Integer.parseInt(buff.readLine());

			int ans = 0;
			if(Y > 0){
				if(X != 0){
					++ans;
				}
			}else if(Y < 0){
				ans += 2;
			}else if(X != 0){
				++ans;
			}

			if(X < 0){
				X *= -1;
			}
			if(Y < 0){
				Y *= -1;
			}

			ans += X / L;
			if(X % L > 0){
				ans++;
			}
			ans += Y / L;
			if(Y % L > 0){
				ans++;
			}

			System.out.println(ans);

		} catch (NumberFormatException e) {

		} catch (IOException e) {

		}
	}
}