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 void main(String[] args) {
		Scanner scan = new Scanner(System.in);
	    int n = scan.nextInt();
	    int[] r = new int[n];
	    for (int i = 0; i < n; i++) {
			r[i] = scan.nextInt();
		}
	  
	    int min = r[0];
		int margin = r[1] - r[0];
		for (int i = 1; i < r.length; i++) {
			margin = Math.max(margin, r[i] - min);
			min = Math.min(min, r[i]);
		}
		
		System.out.println(margin);
	}
}