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 (GCC 5.4.1) (judge verdict: Accepted)

#include<stdio.h>




int main() {
	int N;
	scanf("%d", &N);
	int *H = (int *)malloc(sizeof(int)*(N + 2));
	int hmax = 0;
	H[0] = 0;
	H[N] = 0;
	for (int i = 1; i <= N; i++)
	{
		scanf("%d", &H[i]);
		if (hmax < H[i]) {
			hmax = H[i];
		}
	}

	int cnt = 0;
	int ans = 0;
	for (int i = 1; i <= hmax; i++)
	{
		int tmp = 0;
		for (int j = 1; j <= N + 1; j++)
		{
			if (H[j] >= i && H[j - 1] < i) {
				tmp = 1;
			}
			else if (H[j] < i && H[j - 1] >= i && tmp == 1) {
				cnt++;
			}
		}
	}
	ans = cnt;
	printf("%d\n", ans);
	return 0;
}