Petya and Origami

# 题目描述 Petya 将要举行一场派对，她要发送大量的邀请函给朋友们。 每一张邀请函需要耗费 2 张红色纸，5 张绿色纸和 8 张蓝色纸。 然而，商店里卖纸是一堆一堆卖的，每一堆有 $k$ 张且只含有红，绿，蓝三种颜色之一的纸，Petya 可以选择买哪种颜色的一堆纸。 现在 Petya 要给 $n$ 名朋友发送邀请函，请问她至少要到商店买几堆纸。 # 输入格式 第一行包含两个整数 $n$ , $k$，意义如上文所述。 # 输出格式 一行一个整数，表示 Petya 至少要买几堆纸。 # 数据范围 $1 \leq n,k \leq 10^8$

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.

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.

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

3 5

10

15 6

38

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.