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;

namespace ABC116C
{
    using System;
    using System.Collections.Generic;
    using System.Linq;

    class MainClass
    {
        static int[] s;
        static int[] n;

        public static void Main(string[] args)
        {

            s = Array.ConvertAll(Console.ReadLine().Split().ToArray(), int.Parse);
            n = Array.ConvertAll(Console.ReadLine().Split().ToArray(), int.Parse);

            int ans = 0;
            int tmp = 0;
            int diff = 0;

            for(int i = 0; i < s[0]; i++)
            {
                diff = n[i] - tmp;
                if (diff > 0)
                {
                    ans += diff;
                }
                tmp = n[i];

            }

            Console.WriteLine(ans);
            return;
        }
    }
}