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: Wrong Answer)

import java.util.Scanner;


public class Main {

	public static void main(String[] args) {
		// TODO ?????????????????????????????????????????????

		int n,i,j,a,maxv,minv;
		Scanner sc=new Scanner(System.in);
		n=Integer.parseInt(sc.next());
		int r[]=new int[n];
		for(i=0;i<n;i++){
			r[i]=Integer.parseInt(sc.next());
		}

		maxv=r[1]-r[0];
		minv=r[0];
		for(j=1;j<n-1;j++){
			maxv=Math.max(maxv, r[j]-minv);
			minv=Math.min(minv, r[j]);
		}

		System.out.println(maxv);


	}

}