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;
public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in=new Scanner(System.in);
		int counter;
		counter=in.nextInt();
		int seller,buyer,temp,diff;
		seller=0;
		int pri=0;
		diff=Integer.MIN_VALUE;
		buyer=Integer.MAX_VALUE;
		//long start=System.currentTimeMillis();
		for(int i=0;i<counter;i++) {
			temp=in.nextInt();
			if(i!=0 && diff<temp-pri)
				diff=temp-pri;
			if (temp< buyer && i<counter-1) {
				buyer = temp;
				seller = 0;
				pri=temp;
				continue;
			}
			if (temp>seller) {
				seller = temp;
			}
			if (seller !=0 && diff< seller-buyer) {
				diff= seller - buyer;
			}
			pri=temp;
		}
		System.out.println(diff);
	}
}