Maximum Difference

You are given an array of integers. Your task is to find the maximum difference between any two elements a_i and a_j such that j > i. In other words, you need to compute

$$\max_{i<j} \bigl(a_j - a_i\bigr)$$

If no pair exists that satisfies the condition, the answer is 0.

Example:

Input:
6
4 3 10 2 9 1
Output:
7

</p>

inputFormat

The input is read from standard input (stdin). The first line contains a single integer n which represents the number of elements. The second line contains n space-separated integers.

outputFormat

Output a single integer — the maximum difference between any two elements a_i and a_j (with j > i). Print the result to standard output (stdout).

## sample

6
4 3 10 2 9 1

7