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(void){
  int n;
  int flg=1,cnt=0;
  int i,j;
  scanf("%d",&n);
  int s[n];
  for(i=0;i<n;i++)scanf("%d",&s[i]);
  
  while(1){
    i=0;
    while(s[i]==0 && i<n){
      i++;
    }
    j=i;
    while(s[j]!=0 && j<n){
	  j++;
    }
    if(i<n){
      for(int k=i;k<=j-1;k++){
        s[k]--;
      }
      cnt++;
    }else{
      break;
    }
  }
  
  printf("%d\n",cnt);
  return(0);
}