import java.util.Scanner;

public class No48 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int X = sc.nextInt(); //x座標
		int Y = sc.nextInt(); //y座標
		int L = sc.nextInt(); //一度に動ける距離
		int count = 0; //命令した回数
		
		if(X % L == 0) {
			count += Math.abs(X) / L;
		}else {
			count += Math.abs(X) / L + 1;
		}
		
		if(Y % L == 0) {
			count += Math.abs(Y) / L;
		}else {
			count += Math.abs(Y) / L + 1;
		}
		
		if(X != 0 && Y >= 0) {
			count++;
		}else if(Y < 0 && X != 0) {
			count += 2;
		}
		
		System.out.println(count);
	}
}