Maximum Stock Profit

You are given a list of daily stock prices. Your task is to compute the maximum profit that can be achieved by buying on one day and selling on a later day. If no profit can be made, the answer should be 0.

Formally, given an array of prices, you need to find $$\max_{0 \le i < j < n}(prices[j] - prices[i])$$ If the result is negative, output 0.

Your solution should read input from stdin and write the output to stdout.

inputFormat

The input consists of two lines:

• The first line contains an integer n representing the number of days.
• The second line contains n space-separated integers representing the stock prices on each day.

If n is zero, the second line may be omitted or empty.

outputFormat

Print a single integer representing the maximum profit possible. If no profit can be achieved, print 0.

## sample

6
7 1 5 3 6 4

5

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