Boxes (easy)

There are boxes on the circle. The boxes are numbered from 1 to n (1 <= n <= 1000) in clockwise order. There are balls in the boxes, and the number of all the balls in the boxes is not greater than n . The balls should be displaced in such a way that in each box there remains no more than one ball. In one move we can shift a ball from one box to one of it's neighboring boxes.

Write a program that: reads from the standard input the number of boxes n and the arrangement of balls in the boxes, computes the minimal number of moves necessary to displace the balls in such a way that in each box there remains no more than one ball, writes the result to the standard output.