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)

object Main extends App {
  import java.{ util => ju }
  import scala.annotation._
  import scala.collection._
  import scala.collection.{ mutable => mu }
  import scala.collection.JavaConverters._
  import scala.math._
  import scala.io.StdIn.readLine

  val sc = new ju.Scanner(System.in)

  val n = sc.nextInt()
  val nums = Array.fill(n)(sc.nextInt())

  var maxV = nums(1) - nums(0)
  var minV = Integer.MAX_VALUE

  for (s <- nums) {
    maxV = max(maxV, s - minV)
    minV = min(minV, s)
  }
  println(maxV)
}