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>
#include <stdlib.h>
int main() {
	int i;

	int n;
	int* Rt;
	int dif, maxProfit = -1000000000;
	int min;

	do {
		scanf("%d", &n);
	} while (n < 2 || 200000 < n);

	Rt = (int*)malloc(sizeof(int) * n);

	for (i = 0; i < n; i++) {
		scanf("%d", &Rt[i]);
	}

	min = Rt[0];

	for (i = 1; i < n; i++) {
		dif = Rt[i] - min;
		if (maxProfit < dif) {
			maxProfit = dif;
		}
		if (Rt[i] < min) {
			min = Rt[i];
		}
	}

	printf("%d\n", maxProfit);

	return 0;
}