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 int mp_dp(int[] values) {
		int maxp = values[1]-values[0];
		int minv = min(values[1],values[0]);
		for(int i=2;i<values.length;i++) {
			maxp = max(maxp,values[i]-minv);
			minv=min(minv,values[i]);
		}
		return maxp;
	}
	public static int max(int a,int b) {
		if (a>=b) {
			return a;
		}
		else {
			return b;
		}
	}
	public static int min(int a,int b) {
		if (a>=b) {
			return b;
		}
		else {
			return a;
		}
	}
	public static void main(String[] wjy) {
		Scanner sc = new Scanner(System.in);
		int[] stock = new int[sc.nextInt()];
		for (int i=0;i<stock.length;i++) {
			stock[i]= sc.nextInt();
		}
		sc.close();
		System.out.println(mp_dp(stock));
	}
}