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 void main(String[] args){
	    Scanner sc = new Scanner(System.in);
	    int n = sc.nextInt();
	    int[] R = new int [n];
	    
	    for(int i = 0; i < n; i++) {
	    	R[i] = sc.nextInt();
	       
	    }//for
	    System.out.println(compute_maxprofit(n,R));
	    
	}//main
	
	 public static int compute_maxprofit(int n, int[] R) {
	     int max_profit = -999999999;
	     int m = R[0];
	      for(int i = 1; i < n ; i ++) {
	    	  if(R[i] - m > max_profit) {
	    		 max_profit = R[i] - m;
	    		  
	    	  }//if
	    	  if(R[i] < m) {
	    		  m = R[i];
	    	  }//if
		 
		  
	      }//for
	      return max_profit;
	 }
}