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 MAX(a, b) (a >= b)? a: b;
#define MIN(a, b) (a <= b)? a: b;

int main(void)
{
    int i;

    int data_num;
    scanf("%d", &data_num);

    long rate_min, rate_tmp;
    scanf("%ld %ld", &rate_min, &rate_tmp);
    long range_max = rate_tmp - rate_min;
    rate_min = MIN(rate_min, rate_tmp);

    long range_tmp;
    for (i = 2; i < data_num; i++) {
        scanf("%ld", &rate_tmp);
        range_tmp = rate_tmp - rate_min;
        rate_min = MIN(rate_min, rate_tmp);
        range_max = MAX(range_max, range_tmp);
    }

    printf("%ld\n", range_max);

    return 0;
}