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;
import java.util.ArrayList;
import java.util.List;

public class Main {
	
	private static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	
	public static String[] readStandartInput() throws IOException{
		String str = br.readLine();
		String[] list = str.split(" ");
		
		return list;
	}
	
	public static void main(String[] args) throws NumberFormatException, IOException {
		int n = Integer.valueOf(readStandartInput()[0]);
		List<Integer> list = new ArrayList<>();
		
		for(int i = 0; i < n; i++){
			int a = Integer.valueOf(readStandartInput()[0]);
			list.add(a);
		}
		
		
		int old = list.get(0);
		int max = old;
		int min = old;
		int maxBenefit = 0;
		int maxDelta = Integer.MIN_VALUE;
		
		for(int i = 1; i < list.size(); i++){
			int r = list.get(i);
			int delta = r - old;
			if(maxDelta < delta){
				maxDelta = delta;
			}
			if(r < min){
				min = r;
				max = r;
			}else if(max < r){
				max = r;
				int benefit = max - min;
				if(maxBenefit < benefit){
					maxBenefit = benefit;
				}
			}
			old = r;
		}
		if(maxBenefit == 0){
			maxBenefit = maxDelta;
		}
		
		System.out.println(maxBenefit);
		
		
	}
	
}