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

public class No00000048_Main2 {

	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 cnt = 0;
		if(x != 0 || y != 0) {
			if(y >= 0) {
				if(x != 0) {
					cnt += 1;
				}
			} else {
				cnt += 2;
			}
			cnt += (Math.abs(x) / l) + (Math.abs(x) % l == 0 ? 0 : 1);
			cnt += (Math.abs(y) / l) + (Math.abs(y) % l == 0 ? 0 : 1);
		}

		System.out.println(cnt);

	}

}