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 (Clang 3.8.0) (judge verdict: Accepted)

#include <stdio.h>

int main(){
	int n;
	scanf("%d",&n);
	int h[n];
	for (int i = 0; i < n; ++i)
	{
		scanf("%d",&h[i]);
	}
	int ans = 0;
	for (int i = 0; i < 100000; ++i)
	{
		int count = 0;
		for (int j = 0; j < n; ++j)
		{
			if(count>0&&h[j]==0){
				break;
			}
			if(h[j]>0){
				count++;
				h[j]=h[j]-1;
			}
		}
		if(count==0){
			break;
		}
		ans++;
	}
	printf("%d",ans);
	return 0;
}