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.Scanner;

public class Main{

	public static void main(String[] args){
		Scanner scan=new Scanner(System.in);
		int i,j,n,max=0,min=0,dist=0;
		n=scan.nextInt();
		int r[]=new int [n];
		for(i=0;i<n;i++) {
			r[i]=scan.nextInt();
			if(r[max]<r[i]) {
				max=i;
			}
			if(r[min]>r[i]) {
				min=i;
			}
		}
		if(min<max) {
			System.out.println(r[max]-r[min]);
			scan.close();
			return;
		}
		for(i=0;i<n-1;i++) {
			for(j=i+1;j<n;j++) {
				if(j==1) {
					dist=r[j]-r[i];
				}
				else if(dist<r[j]-r[i]) {
					dist=r[j]-r[i];
				}
			}
		}
		System.out.println(dist);
		scan.close();
	}
}