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.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws Exception {
		//??\??????????????????
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        //????????????????????°?????????
        int num =Integer.parseInt(br.readLine());
        //??????????°???? ???????????????????¨??????????
        int min = Integer.parseInt(br.readLine());
        //?????§?????? ????????????????????????????????????????????§??????????????????????????????????¨??????????
        int maxProfit = -1000000000;
        int currentNum = 0;
        for(int i = 1 ; i < num ; i++){
        	currentNum = Integer.parseInt(br.readLine());
        	maxProfit = Math.max(maxProfit, currentNum - min);
        	min = Math.min(min, currentNum);
        }
        
        System.out.println(maxProfit);

	}

}