import java.util.Scanner;

class No48 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int X = sc.nextInt();
		int Y = sc.nextInt();
		int L = sc.nextInt();

		int changeInDirection = 0;
		if (X > 0 || X < 0) {
			changeInDirection++;
			if (Y < 0) {
				changeInDirection++;
			}
		} else if (Y < 0) {
			changeInDirection++;
		}

		changeInDirection += (Math.abs(X) + Math.abs(Y)) / L;
		if (!((Math.abs(X) + Math.abs(Y)) % L == 0)) {
			changeInDirection++;
		}
		System.out.println(changeInDirection);
	}

}