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.*;
class Main{     
	Scanner sc = new Scanner(System.in);   
	int n; 
	int m=-2000000000;  
	int mini;
	   
	void mp(){  
		n=sc.nextInt();
		mini=sc.nextInt();
		
		for(int i=0; i<n-1; i++){         
			int d=sc.nextInt();
		   	m=maxv(m,d-mini);        
			mini=minv(mini,d);     
		}        
		System.out.println(m); 
		}       
	
		int maxv(int a,int b){    
		if(a>b)return a;     
		else return b;     
		}       
	
		int minv(int a,int b){   
		if(a<b)return a;   
		else return b;     
		}    
	           
	public static void main(String[] args){     
		new Main().mp();     
		} 
	}