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) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[] h = new int[n];
		int MAX = 0;
		for(int i = 0; i < n; i++) {
			h[i]  = sc.nextInt();
			MAX = Math.max(MAX, h[i]);
		}
		int ans = 0;
		for(int i = 0; i < MAX; i++) {
			int tmp = 1;
			int nzero = 0;
			if(h[0] == 0) {
				while(h[nzero] == 0) {
					nzero ++;
				}
			}
			for(int j = nzero; j < n-1; j++) {
				if(h[j] * h[j+1] == 0 && h[j+1] == 0) {
					if(h[j] + h[j+1] != 0) {
						tmp ++;
					}
					
				}
			}
			if(h[n-1] == 0 && h[nzero] != 0) {
				tmp --;
			}
			for(int j = 0; j < n; j++) {
				if(h[j] != 0) {
					h[j] --;
				}
			}
			
			ans += tmp;
			//System.out.println(ans);
		}
		System.out.println(ans);
		sc.close();
	}
	
}