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 Scala (judge verdict: Runtime Error)

import scala.io.Source

object Main{
  def main(args: Array[String]){
    val lines = for{
      in <- Source.stdin.getLines.toList
    }yield in.toInt

    println(rec(lines.tail))
  }

  def rec(list: List[Int]): Int =
    if(list.length == 2) list.last - list.head
    else if(list.last - list.init.min > rec(list.init)) list.last - list.init.min else rec(list.init)
}