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: Wrong Answer)

#include<stdio.h>
int main(void) {
  int N,H[101],i,max=0,min=-1,ans=0;
  scanf("%d",&N);
  for(i=0;i<N;i++)scanf("%d",&H[i]);
  H[N]=0;
  for(i=0;i<N+1;i++) {
    if(max<H[i])max=H[i];
    if((i>0 && H[i]<H[i-1] && H[i]<H[i+1] && i<N) || i==N) {
      min=H[i];
      ans=ans+max-min;
      printf("ans:%d:%d\n",i,ans);
      max=0;
    }
  }
  printf("%d",ans);
}