Problem:
MathJax.Hub.Config({ tex2jax: { inlineMath: [["$","$"], ["\\(","\\)"]], processEscapes: true }});

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.*;

public class Main {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int[] array = new int[2000000];
		int number = in.nextInt();
		
		for( int i = 0; i < number; i ++) {
			
			array[i] = in.nextInt();
		}
		
		int ans = calcMaxDiff(array, number);
		System.out.println(ans);
		}
	
		
		public static int calcMaxDiff(int[] NumsInArray, int n) {
			int maximum = NumsInArray[1] - NumsInArray[0];
			int minimum = NumsInArray[0];
			
			for(int i = 1; i < n; i++) {
				maximum = (maximum > NumsInArray[i] - minimum ? maximum : NumsInArray[i] - minimum);
				minimum = (minimum < NumsInArray[i] ? minimum : NumsInArray[i]);
			}
			return maximum;
		}
	}