Problem Description

You are given an integer array prices, where prices[i] represents the price of a given stock on day i. Your task is to compute the maximum profit you can achieve by completing at most one transaction.

A transaction consists of choosing a single day to buy a stock and a later day to sell it. You are allowed to complete zero or one transaction. If no profit can be made, the maximum profit is 0.

Constraints

• The prices array will have at least one element (n >= 1).
• You must buy the stock before you sell it.

Input

• prices: An array of integers representing daily stock prices.

Output

• An integer representing the maximum possible profit.

Example

• Input: [7, 1, 5, 3, 6, 4]
• Output: 5 (Achieved by buying at price 1 and selling at price 6.)

Edge Cases

• If prices are always decreasing, the maximum profit should be 0.