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 {

	// given n times, and R, an array of currencies/rates
	static int compute_maxprofit(int n, int[] R) {
		int max_profit = -999999999;
		int minprofit = R[0];

		for (int i = 1; i < n; i++) {
			max_profit = Math.max(max_profit, R[i] - minprofit);
			minprofit = Math.min(minprofit, R[i]);

		}
		return max_profit;
	}

	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		int[] R = new int[n];

		for (int i = 0; i < n; i++) {
			R[i] = in.nextInt();
		}
		System.out.println(compute_maxprofit(n, R));
		in.close();
	}
}