Maximum Profit from Stock Prices

You are given a sequence of daily stock prices. Your task is to determine the maximum profit that can be achieved by buying on one day and selling on a later day.

Given an array of integers P representing the stock prices on successive days, you need to find two indices i and j such that i < j and the difference $P[j] - P[i]$ is maximized. If no profit can be made, return 0.

Note: You must buy before you sell.

inputFormat

The input is given in two lines:

• The first line contains a single integer n — the number of days.
• The second line contains n space-separated integers representing the stock prices.

If n is 0, the second line may be empty.

outputFormat

Output a single integer — the maximum profit that can be achieved. If no profit is possible, output 0.

## sample

6
7 1 5 3 6 4

5

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