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.Scanner;
public class Main {

	public static void main(String[] args){
		Scanner stdIn=new Scanner(System.in);
		int N=stdIn.nextInt();
		int h[]=new int[N];
		int z=0,y=0,x=1,max=0,n=1,s=0;
		while(z<N){
			h[z]=stdIn.nextInt();
			if(h[z]>max)
				max=h[z];
			z++;
		}z=0;
		while(x<=max){
			while(y<N){
				if(h[y]<x){
					if(n==0)
						n=1;
				}
				else{
					if(n==1)
						s++;
					n=0;
				}
				y++;
			}
			x++;
			n=1;
			y=0;
			z+=s;
			s=0;
		}
		System.out.println(z);
	}
}