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: Wrong Answer)

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws Exception {
        // TODO ?????????????????????????????????????????????
        
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            int n=0,result=-10000000;
            int[] store=null;
            boolean min_flag=false;
            while ((line = br.readLine()) != null) {
            	n=Integer.parseInt(line);
            	store=new int[n];
            	int min=Integer.parseInt(br.readLine()),max=min;
            	for(int i=1;i<n;i++){
            		int s=Integer.parseInt(br.readLine());
            		if(s<min&&i!=n-1){
            			min=s;
            			max=s;
            			if(i==n-2){
            				max=Integer.parseInt(br.readLine());
            				if(max-min>result){
            					System.out.println(max-min);
            				}else{
            					System.out.println(result);
            				}
            				return;
            			}
            		}else if(s>max){
            			max=s;
            			if(max-min>result){
            				result=max-min;
            			}
            		}
            	}
            	
            	System.out.println(result);
            	break;
            }
        }
    }

}