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: Time Limit Exceeded)

import java.util.Scanner;

public class Main{
	public static void  main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int buy,ben;
		ben = Integer.MIN_VALUE;
		
		int[] R  = new int[n];
		for(int i = 0 ; i < n ; i++ )
		{
			R[i] = sc.nextInt();
		}
		for(int i = 0 ; i < n-1 ; i++ )
		{
			buy = R[i];
			for(int j = i+1 ; j < n ; j++ )
			{
				if( R[j] - R[i] > ben ) ben = R[j]-R[i] ; 
			}
		
		}
		System.out.println(ben);
		
	}
}