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 9.2.1) (judge verdict: Accepted)

#include"bits/stdc++.h"
using namespace std;
typedef long long ll;
#define int ll
const int N=200;
int a[200];
int32_t main()
{
  #ifndef ONLINE_JUDGE
  freopen("in","r",stdin);
  freopen("out","w",stdout);
  #endif
  int n;cin>>n;
  for(int i=0;i<n;i++)
  {
    cin>>a[i];
  }

  int ans=0;
  while(1)
  {
    bool done=0;bool active=0;
    for(int i=0;i<n;i++)
    {
      if(a[i]>=1 and !active){a[i]--;active=1;ans++;done=1;}
      else if(a[i]>=1 and active){a[i]--;}
      else if(a[i]<=0){active=0;}
    }
    if(!done)break;
  }
  cout<<ans;
  
 
  

}