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 maxProfitWhenSell(int[] arr, int maxP, int index, int min) {
		if(index == arr.length - 1) {
			return Math.max(maxP, arr[index] - min);
		}else {
			maxP = Math.max(maxP, arr[index] - min);
			min = Math.min(min, arr[index]);
			return Math.max(maxP, maxProfitWhenSell(arr, maxP, index + 1, min));
		}
		
	}
	public static int maxProfit(int[] arr) {
		int maxP = Integer.MIN_VALUE;
		int min = Integer.MAX_VALUE;
		for (int index = 0; index < arr.length; index += 1) {
			maxP = Math.max(maxP, arr[index] - min);
			min = Math.min(min, arr[index]);
		}
		return maxP;
	}
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int line = Integer.parseInt(sc.nextLine());
		int[] rt = new int[line];
		for (int li = 0; li < line; li += 1) {
			rt[li] = Integer.parseInt(sc.nextLine());
		}
		System.out.println(maxProfit(rt));
	}
}