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 Python (judge verdict: Accepted)

def maximumProfit(A, N):
    minR = A[0]
    minP = A[1] - A[0]
    for i in range(1, N):
        R = A[i] - minR
        if R > minP:
            minP = R
        if A[i] < minR:
            minR = A[i]
    return minP

if __name__ == "__main__":
    N = input()
    A = []
    for i in range(N):
        A.append(input())
    print maximumProfit(A, N)