There is a competition in your brother's school. The students form groups of k-students. Then, every student j^th in the group competes with the j^th of other groups.

Question: Write a program that is going to get information for n students and it finds the sum of group maxes.

Input specification
In the first line, you will be given two integers: The number of students(n) and the number of students in every group (k) where 0 ≤ k ≤ n ≤ 10,000. Then, starting from the next line, you will be given n integers where the numbers are between -2e5 and 2e5.

Output specification:
Show one integer: sum of group maxes.

Explanation: First students the groups are 10, 7 and 9. So, the max of first students is 10. Then the maxes of every j^th students are 10 7 and 5. And the sum is 22.