Competitions

# PP1 and a bit more

# Toasts

You want to roast a few toasts for the upcoming party. There is a frying pan, that can roast at the same time **k** toasts. Roasting the toast from one side takes **2** minutes. We assume that placing a toast into a frying pan, turning and removing it from the pan performed instantly. Write a program that computes the minimum time in minutes for roasting **n** toasts. Toasts should not be removed from the pan sooner or later that **2** minutes required for toasting one side. Each toast should be roasted from both sides.

#### Input

The first line contains two integers **n** and **k** (**0** ≤ **n** ≤ **1000**, **1** ≤ **k** ≤ **50**) - the number of toasts and pan capacity.

#### Output

Print the minimum time in minutes required to roast **n** toasts.

Input example #1

3 2

Output example #1

6