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;

class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int val[] = new int[N];
		int cnt[] = new int[N];
		int val_cnt=0;
		int i, j, x;
		for(i=0; i<N; i++){
			x = sc.nextInt();
			for(j=0; j<val_cnt; j++){
				if(x==val[j]) break;
			}
			if(j==val_cnt){
				val[j] = x;
				val_cnt++;
			}
			cnt[j]++;
		}
		for(i=0, j=1; j<val_cnt; j++){
			if(cnt[i]<cnt[j]) i = j;
		}
		System.out.println(val[i]);
	}
}