Problem:
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Maximum Profit

You can obtain profits from foreign exchange margin transactions. For example, if you buy 1000 dollar at a rate of 100 yen per dollar, and sell them at a rate of 108 yen per dollar, you can obtain (108 - 100) × 1000 = 8000 yen.

Write a program which reads values of a currency $R_t$ at a certain time $t$ ($t = 0, 1, 2, ... n-1$), and reports the maximum value of $R_j - R_i$ where $j > i$ .

Input

The first line contains an integer $n$. In the following $n$ lines, $R_t$ ($t = 0, 1, 2, ... n-1$) are given in order.

Output

Print the maximum value in a line.

Constraints

$2 \leq n \leq 200,000$

$1 \leq R_t \leq 10^9$

Sample Input 1

6
5
3
1
3
4
3

Sample Output 1

3

Sample Input 2

3
4
3
2

Sample Output 2

-1

Solution in JAVA (judge verdict: Accepted)

import java.util.Scanner;

class Main {
	public static void main(String[] args) {

		Scanner scanner = new Scanner(System.in);
		int count = scanner.nextInt() - 2;//???????????°???????´????*???????????????2?????????
		int price = scanner.nextInt(); //????????????
		int changedPrice = scanner.nextInt(); //????????????????±???????
		int profit = changedPrice - price; //????????????????´????????????°

		if (changedPrice < price) {
			price = changedPrice;
		}

		for (int i = 0; i < count; i++) {
			changedPrice = scanner.nextInt();
			if (profit < (changedPrice - price)) {
				profit = changedPrice - price;
			}
			if (changedPrice < price) {
				price = changedPrice;
			}
		}
		System.out.println(profit);
	}
}