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 Ruby (judge verdict: Accepted)

n = gets(chomp:true).to_i

# 最大利益を負の無限大に設定！！！
maxv = -Float::INFINITY

# 最小値を読み込み
minv = gets(chomp:true).to_i

(1...n).each do

  # 比較する価格を読み込み
  price = gets(chomp:true).to_i

  # 最大利益が価格-最小値より小さい場合。最大利益を更新
  maxv < price - minv && maxv = price - minv

  # 最小値が価格より大きい場合、最小値を更新
  minv > price && minv = price

end

puts maxv