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>          // printf(), scanf()

#define MAX_N 200000
#define min(a, b) ((a) < (b) ? a : b)
#define max(a, b) ((a) > (b) ? a : b)

int
main(int argc, char** argv)
{
	int r[MAX_N];
	int n, i;

	int maxv = -1000000000;
	int minv = 0;
	
	scanf("%d", &n);
	for (i = 0; i < n; ++i)
		scanf("%d", &r[i]);

	minv = r[0];
	for (i = 1; i < n; ++i)
	{
		maxv = max(maxv, r[i] - minv);
		minv = min(minv, r[i]);
	}

	printf("%d\n", maxv);
	return 0;
}