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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Linq;
using  System.Collections;
using  System.Collections.Generic;
class Program
{
static void Main(string[] args){
Console.ReadLine();
var d = (Console.ReadLine()).Split(' ').Select((n,m)=> new { h = int.Parse(n),i = m}).ToArray();
Console.WriteLine(Enumerable.Range(0, 100).ToArray().Sum(sh => {
var p = d.Where(a=>a.h>sh).Select(a=>a.i).ToArray();
int pval=-2;
return p.Sum(a=>{
if(a!=pval+1){
 pval=a;
 return 1;
}
 pval=a;
return 0;
});
}));
}
}