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: Time Limit Exceeded)

#include <stdio.h>

int main(void)
{
	int max, wk;
	int a[200000];
	int *pi, *pj, *pe;
	
	scanf("%d", &max);
	for(pi = a, pe = pi + max; pi < pe; pi++){
		scanf("%d", pi);
	}
	
	max = a[1] - a[0];
	for(pj = &a[2]; pj < pe; pj++){
		for(pi = a; pi < pj; pi++){
			wk = *pj - *pi;
			if(max < wk){
				max = wk;
			}
		}
	}
	printf("%d\n", max);
	
	return(0);
}