CF1080A.Petya and Origami

Petya is having a party soon, and he has decided to invite his $n$ friends.

He wants to make invitations in the form of origami. For each invitation, he needs two red sheets, five green sheets, and eight blue sheets. The store sells an infinite number of notebooks of each color, but each notebook consists of only one color with $k$ sheets. That is, each notebook contains $k$ sheets of either red, green, or blue.

Find the minimum number of notebooks that Petya needs to buy to invite all $n$ of his friends.

佩特亚很快就要举办一场派对，他决定邀请他的 $n$ 位朋友。

他打算用折纸的方式制作请柬。每份请柬需要 2 张红色纸、5 张绿色纸和 8 张蓝色纸。商店中每种颜色的笔记本均有无限供应，但每本笔记本只含一种颜色，且每本恰好包含 $k$ 张纸。也就是说，每本笔记本要么含 $k$ 张红色纸，要么含 $k$ 张绿色纸，要么含 $k$ 张蓝色纸。

求佩特亚为邀请全部 $n$ 位朋友所需购买的笔记本的最少数量。

The first line contains two integers $n$ and $k$ ($1\leq n, k\leq 10^8$) — the number of Petya's friends and the number of sheets in each notebook respectively.

第一行包含两个整数 $n$ 和 $k$（$1\leq n, k\leq 10^8$）—— 分别表示佩蒂亚的朋友人数以及每本笔记本的页数。

Print one number — the minimum number of notebooks that Petya needs to buy.

输出一个数字——Petya 需要购买的笔记本的最少数量。

In the first example, we need $2$ red notebooks, $3$ green notebooks, and $5$ blue notebooks.

In the second example, we need $5$ red notebooks, $13$ green notebooks, and $20$ blue notebooks.

在第一个例子中，我们需要 $2$ 本红色笔记本、$3$ 本绿色笔记本和 $5$ 本蓝色笔记本。

在第二个例子中，我们需要 $5$ 本红色笔记本、$13$ 本绿色笔记本和 $20$ 本蓝色笔记本。