#include<stdio.h>

int main() {
	// 宣言
	int controlCnt = 0;
	signed int X = 0;
	signed int Y = 0;
	signed int distance = 0;

	// 入力値受け取り
	scanf("%d", &X);
	scanf("%d", &Y);
	scanf("%d", &distance);

	// X方向
	if (Y >= 0) {
		controlCnt += Y / distance + (Y % distance > 0);
		if (X == 0)
			goto answer;

	}
	else {
		controlCnt ++;
		controlCnt += -Y / distance + (-Y % distance > 0);
		if (X == 0)
			goto answer;
	}

	// Y方向
	controlCnt++;
	if (X > 0)
		controlCnt += X / distance + (X % distance > 0);
	else
		controlCnt += -X / distance + (-X % distance > 0);
	goto answer;

	// 回答表示
answer:
	printf("%d", controlCnt);
	return 0;
}