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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		List<Long> list = new ArrayList<Long>(); 
		br.readLine();
		String str;
		while((str = br.readLine()) != null){
			list.add(Long.valueOf(str));
		}
		int cursor = list.size() - 2;
		long maxProfit = list.get(cursor + 1) - list.get(cursor);
		long a, b;
		long max = (a = list.get(cursor + 1)) > (b = list.get(cursor)) ? a : b;
		cursor--;
		while(cursor >= 0){
			if(max - list.get(cursor) > maxProfit){
				maxProfit = max - list.get(cursor);
			}
			if(list.get(cursor) > max){
				max = list.get(cursor);
			}
			cursor--;
		}
		System.out.println(maxProfit);
	}
}