Minimum Cost to Equalize Array

You are given an array of n integers. Your goal is to make all elements of the array equal using the following operations:

• You can increase a chosen contiguous segment of the array by 1 at a cost of 1 unit per increment.
• You can decrease a chosen contiguous segment by any amount with no cost.

It can be proven that the minimum cost to equalize the array is given by:

\[ \text{cost} = \sum_{i=1}^{n-1} \max(0, a_{i+1} - a_{i}) \]

In other words, iterate through the array from left to right; whenever you encounter an increase, add the difference to the cost. Your task is to compute and output this minimum cost.

inputFormat

The first line of input contains a single integer n (1 ≤ n ≤ 10⁵), the number of elements in the array.

The second line contains n space-separated integers representing the array.

outputFormat

Output a single integer, the minimum cost needed to make all elements of the array equal.

## sample

5
1 2 3 2 1

2