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 Python3 (judge verdict: Wrong Answer)

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def get_maximum_profit(value_list):
    minv = pow(10,9)
    profit = -minv
    for i in range(1, len(value_list)):
        profit = max(profit, value_list[i] - minv) 
        minv = min(minv, value_list[i])
    return profit

def main():
    n_list = int(input())
    target_list = [int(input()) for i in range(n_list)]
    print(get_maximum_profit(target_list))
    
if __name__ == "__main__":
    main()