URI Online Judge | 2351
# Hotel Rewards

**Timelimit: 1**

By Fidel I. Schaposnik Argentina

You are planning to spend your holidays touring Europe, staying each night in a different city for **N** consecutive nights. You have already chosen the hotel you want to stay in for each city, so you know the price **P _{i}** of the room you’ll be staying at during the

You will book your accommodation through a website that has a very convenient rewards program, which works as follows. After staying for a night in a hotel you booked through this website you are awarded one point, and at any time you can exchange **K** of these points in your account for a free night in any hotel (which will however not give you another point).

For example, consider the case with **N** = 6 and **K** = 2 where the prices for the rooms are **P _{1}** = 10,

You want to make a program to find out what the minimum possible cost for your holidays’ accommodation is. You can safely assume that all hotels you want to stay always will have a room available for you, and that the order of the cities you are going to visit cannot be altered.

The first line of input contains two integers **N** and **K**, representing the total number of nights your holidays will last, and the number of points you need in order to get a free night (1 ≤ **N**,**K** ≤ 10^{5}). The second line contains **N** integers **P _{1}**,

Output a line with one integer representing the minimum cost of your accommodation for all of your holidays.

Input Samples | Output Samples |

6 2 |
37 |

6 1 |
25 |

5 5 |
15 |