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Background

一张纸能做s个纸飞机，每个人要做n个纸飞机,团队里有k个人,一包纸里有p张。问你最少买多少包纸，可以完成要求。

注意: 每个人要有足够的纸张.

Description

分析样例

Format

Input

一行输入包含4个整数$k, n, s, p$

Output

一个整数表示最少需要买多少包纸?

Samples

5 3 2 3

4

5 3 100 1

5

Limitation

1s, 1024KiB for each test case.

$1 <= k, n, s, p <= 10^4$