You are the manager of the hotel and you have N customers to serve. Each customer has a happiness quotient (Ci) if the food is served to him at time x. The unhappiness of a customer is defined by |Ci - x|. You must serve all the customers and you can serve them in any order. You have to find the minimum sum of unhappiness.

Note: At a particular time only one customer is served and Each customer takes one unit of time.

Contraint:

1 <= N <=10^3

1<= Ci <=N

Sample input:

4

2 2 3 3

Sample output:

2

Sample input:

4

1 1 1 1

Sample output:

6

Please give suggestions on how to solve this problem efficiently.