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 Fx{
	int a;
	int [] p=new int[200000];
	int ans;
	void rieki() {
		int minv=p[0];
		int maxv=p[1]-p[0];
		for(int j=1;j<a;j++) {
			maxv=Math.max(maxv, p[j]-minv);
			minv=Math.min(minv,p[j]);
		}
		ans=maxv;
	}
}
public class Main{
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		int [] s=new int [n];
		for(int i=0;i<n;i++) {
			s[i]=sc.nextInt();
		}
		Fx f=new Fx();
		f.a=n;
		for(int i=0;i<n;i++) {
			f.p[i]=s[i];

		}
		f.rieki();
		System.out.println(f.ans);
		sc.close();
	}
}