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>
#include <stdlib.h>

int main() {
	int n, t, i;
	int max_profit = 0;
	int *Rt;

	scanf("%d", &n);
	//????????????????????£?¨?
	Rt = (int *)malloc(sizeof(int) * n);
	if (Rt == NULL) exit(0);

	//??\???
	for (t = 0; t < n; t++) {
		scanf("%d", &Rt[t]);
	}
	
	//
	for (t = 0; t < n - 1; t++){
		for (i = t + 1; i < n; i++) {
			if ((t == 0 && i == 1) || max_profit < Rt[i] - Rt[t]) {
				max_profit = Rt[i] - Rt[t];
			}
		}
	}

	//??????
	printf("%d\n", max_profit);

	//?????¢????§£???
	free (Rt);

	return 0;
}