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 nextInt();

int N, H[100], ans, h, i;
char f;

int main(){
	N=nextInt();
	for(i=0; i<N; i++){
		H[i]=nextInt();
	}
	for(h=100; h>=1; h--){
		f=0;
		for(i=0; i<N; i++){
			if(H[i]==h){
				if(!f){ans++;}
				f=1;
				H[i]--;
			}else{
				f=0;
			}
		}
	}
	printf("%d\n", ans);
	return 0;
}

int nextInt(){
	int f=0; char c=getchar();
	while((c<'0')||('9'<c)){c=getchar();}
	while((c>='0')&&(c<='9')){f=f*10+(c-'0'); c=getchar();}
	return f;
}