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 Go (1.6) (judge verdict: Accepted)

package main

import (
    "bufio"
    "os"
    "strings"
    "strconv"
    "fmt"
)


var sc = bufio.NewScanner(os.Stdin)

func readLineToInt() []int {
    sc.Scan()
    line := strings.Split(sc.Text(), " ")
    var intLine []int
    length := len(line)
    for i := 0;i < length; i++ {
        n, _ := strconv.Atoi(line[i])
        intLine = append(intLine, n)
    }
    return intLine
}

func readInt() int {
    sc.Scan()
    str := sc.Text()
    n, _ := strconv.Atoi(str)
    return n
}

func main() {
    readInt()
    hList := readLineToInt()
    cnt := 0
    preValue := 0
    for _, value := range hList {
        if preValue < value {
            cnt += value - preValue
        }
        preValue = value
    }
    fmt.Println(cnt)
}