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;

class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);

        int n = Integer.parseInt(scan.nextLine());
        double Rj = 0;
        double Ri = 0;
        double newR;
        double maxProfit = -1000000000;
        double tmpProfit = -1000000000;
        double tmp = 0;

        int value;
        for (int i=0; i<n; i++){
            newR = Integer.parseInt(scan.nextLine());
            if (i == 0){
                Rj = newR;
                Ri = newR;
                continue;
            }
            if (newR < Ri){
                tmp = newR - Ri;
                if (tmp > tmpProfit)
                    tmpProfit = tmp;
                Ri = newR;
                Rj = newR;
                continue;
            }
            if (newR >= Rj){
                Rj = newR;
                tmp = Rj - Ri;
                if (tmp > maxProfit)
                    maxProfit = tmp;
                continue;
            }
        }

        if (tmpProfit > maxProfit)
            maxProfit = tmpProfit;
        else if (tmpProfit == maxProfit)
            maxProfit = 0;

        System.out.println((int)(maxProfit));
    }
}