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 Kotlin (1.0.0) (judge verdict: Accepted)

fun intList() = readLine()?.split(" ")?.map(String::toInt) ?: TODO()
fun main(args: Array<String>) {
    val n = readLine()?.toInt() ?: return
    val h = intList()
    val array = Array(n) { h[it] }
    var count = 0
    while (true) {
        var s = -1
        var w = false
        0.until(n).forEach {
            if (array[it] != 0) {
                w = true
                array[it]--
            } else {
                if (w) {
                    count++
                    s = it
                    w = false
                }
            }
        }
        if (w) {
            count++
        }
        if (array.sum() == 0) {
            break
        }
    }

    println(count.toString())
}