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.*;


class Main {

    public static void main(String[] args) throws Exception {

        Scanner sc = new Scanner(System.in);

        int[] ls = new int[sc.nextInt()];

        ls[0] = sc.nextInt();
        ls[1] = sc.nextInt();

        int maxProfit = ls[1] - ls[0];

        int index = 2;
        while(sc.hasNextInt()){
            int next = sc.nextInt();


            for(int i = 0; i < index; i++) {
                int profit = next - ls[i];
                maxProfit = Math.max(profit, maxProfit);
            }

            ls[index] = next;
            index++;
        }


        System.out.println(maxProfit);
    }
}