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 C (judge verdict: Accepted)

#include <stdio.h>
#define N 200000


int n, j,maxv,minv;
int R[N];
int main(void)
{
	
	
	scanf("%d",&n);
	
	
	for(j = 0; j < n; j++){
	   
	   scanf("%d",&R[j]);
	
	}
	maxv = R[1]- R[0];
	minv = R[0];
	
	
	
	for(j = 1; j < n; j++){
	   
	   
	   if(maxv < R[j] - minv){
	    maxv = R[j] - minv;
	
	    } else { maxv = maxv;
	    
	    }
	    
	    
	    if(minv > R[j]){
	    minv = R[j];
	    
	    } else { minv = minv;
	
	    }
	
	}
	
	
	printf("%d\n", maxv);
	return 0;
}