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.IOException;
import java.io.InputStreamReader;

public class Main {

	public static final int BIG_NUM  = 2000000000;
	public static final int MOD  = 1000000007;

	public static void main(String[] args) {


		int N,tmp,maximum = -BIG_NUM,minimum = BIG_NUM;
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		try {
			N = Integer.parseInt(br.readLine());

			for(int loop = 0; loop < N; loop++){
				tmp = Integer.parseInt(br.readLine());
				maximum = Math.max(maximum, tmp-minimum);
				minimum = Math.min(minimum, tmp);
			}
		} catch (NumberFormatException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}

		System.out.println(maximum);
	}
}