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.Arrays;
import java.util.Scanner;

public class Main {
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = Integer.parseInt(sc.next());
		
		int[] height = new int[n];
		
		
		for(int i = 0; i < n; i++) {
			height[i] = sc.nextInt();
		}
		
		int[] allzero = new int[n];
		Arrays.fill(allzero, 0);
		
		int count = 0;
		while(true) {
			
			if(Arrays.equals(height, allzero)) {
				break;
			}
			
			for(int i = 0; i < n; i++) {
				int f = height[i];
				
				if(f > 0){
					try{
						if(height[i + 1] == 0){
							count++;
						}
					}catch (Exception e){
						count++;
					}
					
					height[i]--;
				}else{
					continue;
				}
			}
		}
		System.out.println(count);
	}
}