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;

public class Main{
	public static int profit(int[] prices){
		int[] sell = new int[prices.length];
		int min = prices[0]; 
		sell[0] = 0 - prices[0];
		for(int i = 1; i < prices.length; i++)
		{
			if(sell[i-1] < prices[i]-min)
			{
				sell[i] = prices[i] - min;
			}else
			{
				sell[i] = sell[i-1];
			}
			if(min > prices[i])
			{
				min = prices[i];
			}
		}
		return sell[prices.length - 1];
	}
	
	public static void main(String[] args)
	{
		Scanner in = new Scanner(System.in);
		int length = in.nextInt();
		
		int[] prices = new int[length];
		for(int i = 0; i < length; i++)
		{
			//System.out.print(i);
			prices[i] = in.nextInt();
		}
		
		System.out.println(profit(prices));
	}
}