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: Time Limit Exceeded)

object Main {
  def main(args: Array[String]): Unit = {
    val sc = new java.util.Scanner(System.in)
    val sz = sc.nextInt
    val list = List.fill(sz)(sc.nextInt)

    val max = list.max
    val maxi = list.indexOf(max)
    val min = list.min
    val mini = list.indexOf(min)
    if(mini <= maxi) {
        println(max-min)
        return
    }

    var ret = Int.MinValue
    for (i <- 0 until list.length-1) {
        var maxv = Int.MinValue
        (i+1 to list.length-1).foreach( index => if(list(index)>maxv)maxv=list(index))
        val t = maxv - list(i)
        if(t>ret) ret = t
    }
 
    println(ret)
  }
}