Given an array of n integers, you are asked to make it non-decreasing. You are allowed to add 1 to any element in the array as many times as you want. Each time you add 1 to an element, you pay $1. You’d like to make the array non-decreasing but with minimal cost. Can you calculate the minimum amount it will cost you to transform the array?

Input

The first line of the input contains a single integer n (2 ≤ n ≤ ) - the number of elements in the array.

The second line of the input contains n space-separated integers ( ≤ ≤ ) - array elements.

Output

The program should print the minimal cost to transform the array into a non-decreasing sequence of numbers.