Problem:
Score : 300 points

Problem Statement

In a flower bed, there are N flowers, numbered 1,2,......,N. Initially, the heights of all flowers are 0.
You are given a sequence h=\{h_1,h_2,h_3,......\} as input. You would like to change the height of Flower k to h_k for all k (1 \leq k \leq N), by repeating the following "watering" operation:

Specify integers l and r. Increase the height of Flower x by 1 for all x such that l \leq x \leq r.

Find the minimum number of watering operations required to satisfy the condition.

Constraints

1 \leq N \leq 100

0 \leq h_i \leq 100

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
h_1 h_2 h_3 ...... h_N

Output

Print the minimum number of watering operations required to satisfy the condition.

Sample Input 1

4
1 2 2 1

Sample Output 1

2

The minimum number of watering operations required is 2.
One way to achieve it is:

Perform the operation with (l,r)=(1,3).

Perform the operation with (l,r)=(2,4).

Sample Input 2

5
3 1 2 3 1

Sample Output 2

5

Sample Input 3

8
4 23 75 0 23 96 50 100

Sample Output 3

221

Solution in Scala (2.11.7) (judge verdict: Wrong Answer)

object Main extends App {
  var n = scala.io.StdIn.readInt()
  var s = scala.io.StdIn.readLine()
  val inputArray =  s.split(" ").map(_.toInt)
  var i = 0

  def judgeWater(s: Seq[Int]): Seq[Int] = {
    var returnSeq = Seq.empty[Int]
    var stopFlg = false
    for(i<-0 to s.size - 1) {
      if (s(i) == 0 || stopFlg) {
        returnSeq :+= s(i)
      } else if (i == (s.size - 1) && !stopFlg) {
        returnSeq :+= s(i) - 1
      } else if (s(i + 1) == 0 && !stopFlg) {
        stopFlg = true
        returnSeq :+= s(i) - 1
      } else {
        returnSeq :+= s(i) - 1
      }
    }
    returnSeq
  }
  def judgeSeq(seqH: Seq[Int]): Unit = {
    i += 1
    val seqAfterWater = judgeWater(seqH)
    if (seqAfterWater.filterNot(_ == 0).nonEmpty) {
      judgeSeq(seqAfterWater)
    } else {
      println(i)
    }
  }
  judgeSeq(inputArray)
}