Score : 100 points

Problem Statement

Takahashi loves takoyaki - a ball-shaped snack.

With a takoyaki machine, he can make at most X pieces of takoyaki at a time, taking T minutes regardless of the number of pieces to make.

How long does it take to make N takoyaki?

Constraints

  • 1 \leq N,X,T \leq 1000
  • All values in input are integers.

Input

Input is given from Standard Input in the following format:

N X T

Output

Print an integer representing the minimum number of minutes needed to make N pieces of takoyaki.

Sample Input 1

20 12 6

Sample Output 1

12

He can make 12 pieces of takoyaki in the first 6 minutes and 8 more in the next 6 minutes, so he can make 20 in a total of 12 minutes.

Note that being able to make 12 in 6 minutes does not mean he can make 2 in 1 minute.

Sample Input 2

1000 1 1000

Sample Output 2

1000000

It seems to take a long time to make this kind of takoyaki.