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>
#define min(a,b) (a)<(b)?(a):(b)
int main(void)
{
  int n,h[110]={},min,ans=0,i=0,j=0;
  scanf("%d",&n);
  for(i=0;i<n;i++){
    scanf("%d",&h[i]);
  }
  i=0;
  while(i<n){
    while(h[i]){
      j=i;
      min=h[j];
      while(h[j]){
        min=min(min,h[j]);
        j++;
      }
      j=i;
      while(h[j]){
        h[j]-=min;
        j++;
      }
      ans+=min;
    }
    i++;
  }
  printf("%d",ans);
  return 0;
}