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: Accepted)

import java.util.Scanner

object Main extends App {

  val sc = new Scanner(System.in)

  def nextInt() = sc.next.toInt

  def maxProfit(n: Int, maxv: Int, minv: Int): Int = {
    if (n == 0)
      maxv
    else {
      val r = nextInt
      maxProfit(n - 1, maxv max (r - minv), minv min r)
    }
  }

  val n = nextInt
  val r0 = nextInt
  val r1 = nextInt

  println(maxProfit(n - 2, r1 - r0, r0 min r1))
}