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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;
public class Main {
	public static void main(String[] args)
	{
		//変数
		//int count=0;
		//boolean sw=false;
		int answer=0;
		//String answer="NO";
		//List<Integer> h=new ArrayList<Integer>();
		//int af=Integer.MAX_VALUE;
		int N=0;
		int v=0;
		int e=0;
		//int t[]=new int[(int)Math.pow(10,5)];
		//入力
		Scanner sc = new Scanner(System.in);
		N=sc.nextInt();
		int h[]=new int[N];
		for(int i=0;i<N;i++)
		{
			h[i]=sc.nextInt();
		}
		//int a=sc.nextInt();
		//String S=sc.next();
		//int [][] cost =new int[N-1][2];
		
		//処理
		for(int i=0;i<N;i++)
		{
			v+=h[i];
		}
		for(int i=1;i<N;i++)
		{
			e+=Math.min(h[i-1],h[i]);
		}
		answer=v-e;
		// 出力
		System.out.println(answer);
	}
}