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: Accepted)

# -*- coding=utf-8 -*-
price = [int(input()) for p in range(int(input()))]

# N ^ 2 のコード → ダメダメ
# max_ = price[1] - price[0]
# for i in range(1, len(price)):
#     for j in range(0, i):
#         if price[i] - price[j] >= max_:
#             max_ = price[i] - price[j]

# Nのコード　→ いけるぞ！
# まずは最小値を調査
min_ = price[0]
max_ = -1000000000000
for i in range(1, len(price)):
    if price[i] - min_ > max_:
        max_ = price[i] - min_

    if price[i] < min_:
        min_ = price[i]

print(max_)